diff --git a/Cargo.lock b/Cargo.lock
index 899435a66ba..f4eb6fc7f49 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -1119,10 +1119,12 @@ name = "builder_client"
 version = "0.1.0"
 dependencies = [
  "eth2",
+ "ethereum_ssz",
  "lighthouse_version",
  "reqwest",
  "sensitive_url",
  "serde",
+ "serde_json",
 ]
 
 [[package]]
diff --git a/beacon_node/builder_client/Cargo.toml b/beacon_node/builder_client/Cargo.toml
index 3531e81c847..1920bd0ebb2 100644
--- a/beacon_node/builder_client/Cargo.toml
+++ b/beacon_node/builder_client/Cargo.toml
@@ -6,7 +6,9 @@ authors = ["Sean Anderson <sean@sigmaprime.io>"]
 
 [dependencies]
 eth2 = { workspace = true }
+ethereum_ssz = { workspace = true }
 lighthouse_version = { workspace = true }
 reqwest = { workspace = true }
 sensitive_url = { workspace = true }
 serde = { workspace = true }
+serde_json = { workspace = true }
diff --git a/beacon_node/builder_client/src/lib.rs b/beacon_node/builder_client/src/lib.rs
index 91ee00a65f7..5f64ac7e43c 100644
--- a/beacon_node/builder_client/src/lib.rs
+++ b/beacon_node/builder_client/src/lib.rs
@@ -1,16 +1,24 @@
 use eth2::types::builder_bid::SignedBuilderBid;
+use eth2::types::fork_versioned_response::EmptyMetadata;
 use eth2::types::{
-    EthSpec, ExecutionBlockHash, ForkVersionedResponse, PublicKeyBytes,
-    SignedValidatorRegistrationData, Slot,
+    ContentType, EthSpec, ExecutionBlockHash, ForkName, ForkVersionDecode, ForkVersionDeserialize,
+    ForkVersionedResponse, PublicKeyBytes, SignedValidatorRegistrationData, Slot,
 };
 use eth2::types::{FullPayloadContents, SignedBlindedBeaconBlock};
 pub use eth2::Error;
-use eth2::{ok_or_error, StatusCode, CONSENSUS_VERSION_HEADER};
-use reqwest::header::{HeaderMap, HeaderValue};
+use eth2::{
+    ok_or_error, StatusCode, CONSENSUS_VERSION_HEADER, CONTENT_TYPE_HEADER,
+    JSON_CONTENT_TYPE_HEADER, SSZ_CONTENT_TYPE_HEADER,
+};
+use reqwest::header::{HeaderMap, HeaderValue, ACCEPT};
 use reqwest::{IntoUrl, Response};
 use sensitive_url::SensitiveUrl;
 use serde::de::DeserializeOwned;
 use serde::Serialize;
+use ssz::Encode;
+use std::str::FromStr;
+use std::sync::atomic::{AtomicBool, Ordering};
+use std::sync::Arc;
 use std::time::Duration;
 
 pub const DEFAULT_TIMEOUT_MILLIS: u64 = 15000;
@@ -49,6 +57,7 @@ pub struct BuilderHttpClient {
     server: SensitiveUrl,
     timeouts: Timeouts,
     user_agent: String,
+    ssz_enabled: Arc<AtomicBool>,
 }
 
 impl BuilderHttpClient {
@@ -64,6 +73,7 @@ impl BuilderHttpClient {
             server,
             timeouts: Timeouts::new(builder_header_timeout),
             user_agent,
+            ssz_enabled: Arc::new(false.into()),
         })
     }
 
@@ -71,6 +81,78 @@ impl BuilderHttpClient {
         &self.user_agent
     }
 
+    fn fork_name_from_header(&self, headers: &HeaderMap) -> Result<Option<ForkName>, String> {
+        headers
+            .get(CONSENSUS_VERSION_HEADER)
+            .map(|fork_name| {
+                fork_name
+                    .to_str()
+                    .map_err(|e| e.to_string())
+                    .and_then(ForkName::from_str)
+            })
+            .transpose()
+    }
+
+    fn content_type_from_header(&self, headers: &HeaderMap) -> ContentType {
+        let Some(content_type) = headers.get(CONTENT_TYPE_HEADER).map(|content_type| {
+            let content_type = content_type.to_str();
+            match content_type {
+                Ok(SSZ_CONTENT_TYPE_HEADER) => ContentType::Ssz,
+                _ => ContentType::Json,
+            }
+        }) else {
+            return ContentType::Json;
+        };
+        content_type
+    }
+
+    async fn get_with_header<
+        T: DeserializeOwned + ForkVersionDecode + ForkVersionDeserialize,
+        U: IntoUrl,
+    >(
+        &self,
+        url: U,
+        timeout: Duration,
+        headers: HeaderMap,
+    ) -> Result<ForkVersionedResponse<T>, Error> {
+        let response = self
+            .get_response_with_header(url, Some(timeout), headers)
+            .await?;
+
+        let headers = response.headers().clone();
+        let response_bytes = response.bytes().await?;
+
+        let Ok(Some(fork_name)) = self.fork_name_from_header(&headers) else {
+            // if no fork version specified, attempt to fallback to JSON
+            self.ssz_enabled.store(false, Ordering::SeqCst);
+            return serde_json::from_slice(&response_bytes).map_err(Error::InvalidJson);
+        };
+
+        let content_type = self.content_type_from_header(&headers);
+
+        match content_type {
+            ContentType::Ssz => {
+                self.ssz_enabled.store(true, Ordering::SeqCst);
+                T::from_ssz_bytes_by_fork(&response_bytes, fork_name)
+                    .map(|data| ForkVersionedResponse {
+                        version: Some(fork_name),
+                        metadata: EmptyMetadata {},
+                        data,
+                    })
+                    .map_err(Error::InvalidSsz)
+            }
+            ContentType::Json => {
+                self.ssz_enabled.store(false, Ordering::SeqCst);
+                serde_json::from_slice(&response_bytes).map_err(Error::InvalidJson)
+            }
+        }
+    }
+
+    /// Return `true` if the most recently received response from the builder had SSZ Content-Type.
+    pub fn is_ssz_enabled(&self) -> bool {
+        self.ssz_enabled.load(Ordering::SeqCst)
+    }
+
     async fn get_with_timeout<T: DeserializeOwned, U: IntoUrl>(
         &self,
         url: U,
@@ -83,6 +165,21 @@ impl BuilderHttpClient {
             .map_err(Into::into)
     }
 
+    /// Perform a HTTP GET request, returning the `Response` for further processing.
+    async fn get_response_with_header<U: IntoUrl>(
+        &self,
+        url: U,
+        timeout: Option<Duration>,
+        headers: HeaderMap,
+    ) -> Result<Response, Error> {
+        let mut builder = self.client.get(url);
+        if let Some(timeout) = timeout {
+            builder = builder.timeout(timeout);
+        }
+        let response = builder.headers(headers).send().await.map_err(Error::from)?;
+        ok_or_error(response).await
+    }
+
     /// Perform a HTTP GET request, returning the `Response` for further processing.
     async fn get_response_with_timeout<U: IntoUrl>(
         &self,
@@ -112,6 +209,32 @@ impl BuilderHttpClient {
         ok_or_error(response).await
     }
 
+    async fn post_ssz_with_raw_response<U: IntoUrl>(
+        &self,
+        url: U,
+        ssz_body: Vec<u8>,
+        mut headers: HeaderMap,
+        timeout: Option<Duration>,
+    ) -> Result<Response, Error> {
+        let mut builder = self.client.post(url);
+        if let Some(timeout) = timeout {
+            builder = builder.timeout(timeout);
+        }
+
+        headers.insert(
+            CONTENT_TYPE_HEADER,
+            HeaderValue::from_static(SSZ_CONTENT_TYPE_HEADER),
+        );
+
+        let response = builder
+            .headers(headers)
+            .body(ssz_body)
+            .send()
+            .await
+            .map_err(Error::from)?;
+        ok_or_error(response).await
+    }
+
     async fn post_with_raw_response<T: Serialize, U: IntoUrl>(
         &self,
         url: U,
@@ -152,6 +275,42 @@ impl BuilderHttpClient {
         Ok(())
     }
 
+    /// `POST /eth/v1/builder/blinded_blocks` with SSZ serialized request body
+    pub async fn post_builder_blinded_blocks_ssz<E: EthSpec>(
+        &self,
+        blinded_block: &SignedBlindedBeaconBlock<E>,
+    ) -> Result<FullPayloadContents<E>, Error> {
+        let mut path = self.server.full.clone();
+
+        let body = blinded_block.as_ssz_bytes();
+
+        path.path_segments_mut()
+            .map_err(|()| Error::InvalidUrl(self.server.clone()))?
+            .push("eth")
+            .push("v1")
+            .push("builder")
+            .push("blinded_blocks");
+
+        let mut headers = HeaderMap::new();
+        if let Ok(value) = HeaderValue::from_str(&blinded_block.fork_name_unchecked().to_string()) {
+            headers.insert(CONSENSUS_VERSION_HEADER, value);
+        }
+
+        let result = self
+            .post_ssz_with_raw_response(
+                path,
+                body,
+                headers,
+                Some(self.timeouts.post_blinded_blocks),
+            )
+            .await?
+            .bytes()
+            .await?;
+
+        FullPayloadContents::from_ssz_bytes_by_fork(&result, blinded_block.fork_name_unchecked())
+            .map_err(Error::InvalidSsz)
+    }
+
     /// `POST /eth/v1/builder/blinded_blocks`
     pub async fn post_builder_blinded_blocks<E: EthSpec>(
         &self,
@@ -202,7 +361,17 @@ impl BuilderHttpClient {
             .push(format!("{parent_hash:?}").as_str())
             .push(pubkey.as_hex_string().as_str());
 
-        let resp = self.get_with_timeout(path, self.timeouts.get_header).await;
+        let mut headers = HeaderMap::new();
+        if let Ok(ssz_content_type_header) = HeaderValue::from_str(&format!(
+            "{}; q=1.0,{}; q=0.9",
+            SSZ_CONTENT_TYPE_HEADER, JSON_CONTENT_TYPE_HEADER
+        )) {
+            headers.insert(ACCEPT, ssz_content_type_header);
+        };
+
+        let resp = self
+            .get_with_header(path, self.timeouts.get_header, headers)
+            .await;
 
         if matches!(resp, Err(Error::StatusCode(StatusCode::NO_CONTENT))) {
             Ok(None)
diff --git a/beacon_node/execution_layer/src/lib.rs b/beacon_node/execution_layer/src/lib.rs
index d5fef4c5aaa..4e0fe1de16b 100644
--- a/beacon_node/execution_layer/src/lib.rs
+++ b/beacon_node/execution_layer/src/lib.rs
@@ -1900,11 +1900,18 @@ impl<E: EthSpec> ExecutionLayer<E> {
         if let Some(builder) = self.builder() {
             let (payload_result, duration) =
                 timed_future(metrics::POST_BLINDED_PAYLOAD_BUILDER, async {
-                    builder
-                        .post_builder_blinded_blocks(block)
-                        .await
-                        .map_err(Error::Builder)
-                        .map(|d| d.data)
+                    if builder.is_ssz_enabled() {
+                        builder
+                            .post_builder_blinded_blocks_ssz(block)
+                            .await
+                            .map_err(Error::Builder)
+                    } else {
+                        builder
+                            .post_builder_blinded_blocks(block)
+                            .await
+                            .map_err(Error::Builder)
+                            .map(|d| d.data)
+                    }
                 })
                 .await;
 
diff --git a/beacon_node/execution_layer/src/test_utils/mock_builder.rs b/beacon_node/execution_layer/src/test_utils/mock_builder.rs
index 3540909fe46..f07ee7ac6f8 100644
--- a/beacon_node/execution_layer/src/test_utils/mock_builder.rs
+++ b/beacon_node/execution_layer/src/test_utils/mock_builder.rs
@@ -1,15 +1,20 @@
 use crate::test_utils::{DEFAULT_BUILDER_PAYLOAD_VALUE_WEI, DEFAULT_JWT_SECRET};
 use crate::{Config, ExecutionLayer, PayloadAttributes, PayloadParameters};
+use bytes::Bytes;
 use eth2::types::PublishBlockRequest;
 use eth2::types::{
     BlobsBundle, BlockId, BroadcastValidation, EventKind, EventTopic, FullPayloadContents,
     ProposerData, StateId, ValidatorId,
 };
-use eth2::{BeaconNodeHttpClient, Timeouts, CONSENSUS_VERSION_HEADER};
+use eth2::{
+    BeaconNodeHttpClient, Timeouts, CONSENSUS_VERSION_HEADER, CONTENT_TYPE_HEADER,
+    SSZ_CONTENT_TYPE_HEADER,
+};
 use fork_choice::ForkchoiceUpdateParameters;
 use parking_lot::RwLock;
 use sensitive_url::SensitiveUrl;
 use slog::{debug, error, info, warn, Logger};
+use ssz::Encode;
 use std::collections::HashMap;
 use std::fmt::Debug;
 use std::future::Future;
@@ -26,11 +31,12 @@ use types::builder_bid::{
 };
 use types::{
     Address, BeaconState, ChainSpec, Epoch, EthSpec, ExecPayload, ExecutionPayload,
-    ExecutionPayloadHeaderRefMut, ExecutionRequests, ForkName, ForkVersionedResponse, Hash256,
-    PublicKeyBytes, Signature, SignedBlindedBeaconBlock, SignedRoot,
-    SignedValidatorRegistrationData, Slot, Uint256,
+    ExecutionPayloadHeaderRefMut, ExecutionRequests, ForkName, ForkVersionDecode,
+    ForkVersionedResponse, Hash256, PublicKeyBytes, Signature, SignedBlindedBeaconBlock,
+    SignedRoot, SignedValidatorRegistrationData, Slot, Uint256,
 };
 use types::{ExecutionBlockHash, SecretKey};
+use warp::reply::{self, Reply};
 use warp::{Filter, Rejection};
 
 pub const DEFAULT_FEE_RECIPIENT: Address = Address::repeat_byte(42);
@@ -955,6 +961,33 @@ pub fn serve<E: EthSpec>(
         )
         .boxed();
 
+    let blinded_block_ssz = prefix
+        .and(warp::path("blinded_blocks"))
+        .and(warp::body::bytes())
+        .and(warp::header::header::<ForkName>(CONSENSUS_VERSION_HEADER))
+        .and(warp::path::end())
+        .and(ctx_filter.clone())
+        .and_then(
+            |block_bytes: Bytes, fork_name: ForkName, builder: MockBuilder<E>| async move {
+                let block =
+                    SignedBlindedBeaconBlock::<E>::from_ssz_bytes_by_fork(&block_bytes, fork_name)
+                        .map_err(|e| warp::reject::custom(Custom(format!("{:?}", e))))?;
+                let payload = builder
+                    .submit_blinded_block(block)
+                    .await
+                    .map_err(|e| warp::reject::custom(Custom(e)))?;
+
+                Ok::<_, warp::reject::Rejection>(
+                    warp::http::Response::builder()
+                        .status(200)
+                        .body(payload.as_ssz_bytes())
+                        .map(add_ssz_content_type_header)
+                        .map(|res| add_consensus_version_header(res, fork_name))
+                        .unwrap(),
+                )
+            },
+        );
+
     let blinded_block =
         prefix
             .and(warp::path("blinded_blocks"))
@@ -1007,35 +1040,47 @@ pub fn serve<E: EthSpec>(
         )
         .and(warp::path::end())
         .and(ctx_filter.clone())
+        .and(warp::header::optional::<eth2::types::Accept>("accept"))
         .and_then(
             |slot: Slot,
              parent_hash: ExecutionBlockHash,
              pubkey: PublicKeyBytes,
-             builder: MockBuilder<E>| async move {
+             builder: MockBuilder<E>,
+             accept_header: Option<eth2::types::Accept>| async move {
                 let fork_name = builder.fork_name_at_slot(slot);
                 let signed_bid = builder
                     .get_header(slot, parent_hash, pubkey)
                     .await
                     .map_err(|e| warp::reject::custom(Custom(e)))?;
-
-                let resp: ForkVersionedResponse<_> = ForkVersionedResponse {
-                    version: Some(fork_name),
-                    metadata: Default::default(),
-                    data: signed_bid,
-                };
-                let json_bid = serde_json::to_string(&resp)
-                    .map_err(|_| reject("coudn't serialize signed bid"))?;
-                Ok::<_, Rejection>(
-                    warp::http::Response::builder()
-                        .status(200)
-                        .body(json_bid)
-                        .unwrap(),
-                )
+                let accept_header = accept_header.unwrap_or(eth2::types::Accept::Any);
+                match accept_header {
+                    eth2::types::Accept::Ssz => Ok::<_, Rejection>(
+                        warp::http::Response::builder()
+                            .status(200)
+                            .body(signed_bid.as_ssz_bytes())
+                            .map(add_ssz_content_type_header)
+                            .map(|res| add_consensus_version_header(res, fork_name))
+                            .unwrap(),
+                    ),
+                    eth2::types::Accept::Json | eth2::types::Accept::Any => {
+                        let resp: ForkVersionedResponse<_> = ForkVersionedResponse {
+                            version: Some(fork_name),
+                            metadata: Default::default(),
+                            data: signed_bid,
+                        };
+                        Ok::<_, Rejection>(warp::reply::json(&resp).into_response())
+                    }
+                }
             },
         );
 
     let routes = warp::post()
-        .and(validators.or(blinded_block))
+        // Routes which expect `application/octet-stream` go within this `and`.
+        .and(
+            warp::header::exact(CONTENT_TYPE_HEADER, SSZ_CONTENT_TYPE_HEADER)
+                .and(blinded_block_ssz),
+        )
+        .or(validators.or(blinded_block))
         .or(warp::get().and(status).or(header))
         .map(|reply| warp::reply::with_header(reply, "Server", "lighthouse-mock-builder-server"));
 
@@ -1048,3 +1093,13 @@ pub fn serve<E: EthSpec>(
 fn reject(msg: &'static str) -> Rejection {
     warp::reject::custom(Custom(msg.to_string()))
 }
+
+/// Add the 'Content-Type application/octet-stream` header to a response.
+fn add_ssz_content_type_header<T: Reply>(reply: T) -> warp::reply::Response {
+    reply::with_header(reply, CONTENT_TYPE_HEADER, SSZ_CONTENT_TYPE_HEADER).into_response()
+}
+
+/// Add the `Eth-Consensus-Version` header to a response.
+fn add_consensus_version_header<T: Reply>(reply: T, fork_name: ForkName) -> warp::reply::Response {
+    reply::with_header(reply, CONSENSUS_VERSION_HEADER, fork_name.to_string()).into_response()
+}
diff --git a/beacon_node/store/src/hot_cold_store.rs b/beacon_node/store/src/hot_cold_store.rs
index 75251cb5fb4..7928957571b 100644
--- a/beacon_node/store/src/hot_cold_store.rs
+++ b/beacon_node/store/src/hot_cold_store.rs
@@ -662,7 +662,9 @@ impl<E: EthSpec, Hot: ItemStore<E>, Cold: ItemStore<E>> HotColdDB<E, Hot, Cold>
             .hot_db
             .get_bytes(ExecutionPayload::<E>::db_column(), key)?
         {
-            Some(bytes) => Ok(Some(ExecutionPayload::from_ssz_bytes(&bytes, fork_name)?)),
+            Some(bytes) => Ok(Some(ExecutionPayload::from_ssz_bytes_by_fork(
+                &bytes, fork_name,
+            )?)),
             None => Ok(None),
         }
     }
diff --git a/common/eth2/src/lib.rs b/common/eth2/src/lib.rs
index af8573a5789..1cf59903d3c 100644
--- a/common/eth2/src/lib.rs
+++ b/common/eth2/src/lib.rs
@@ -48,6 +48,7 @@ pub const CONSENSUS_BLOCK_VALUE_HEADER: &str = "Eth-Consensus-Block-Value";
 
 pub const CONTENT_TYPE_HEADER: &str = "Content-Type";
 pub const SSZ_CONTENT_TYPE_HEADER: &str = "application/octet-stream";
+pub const JSON_CONTENT_TYPE_HEADER: &str = "application/json";
 
 #[derive(Debug)]
 pub enum Error {
@@ -111,9 +112,9 @@ impl Error {
             Error::InvalidSignatureHeader => None,
             Error::MissingSignatureHeader => None,
             Error::InvalidJson(_) => None,
+            Error::InvalidSsz(_) => None,
             Error::InvalidServerSentEvent(_) => None,
             Error::InvalidHeaders(_) => None,
-            Error::InvalidSsz(_) => None,
             Error::TokenReadError(..) => None,
             Error::NoServerPubkey | Error::NoToken => None,
         }
diff --git a/common/eth2/src/types.rs b/common/eth2/src/types.rs
index c6e95e1ba30..59374f629d6 100644
--- a/common/eth2/src/types.rs
+++ b/common/eth2/src/types.rs
@@ -1664,7 +1664,7 @@ impl<E: EthSpec> FullBlockContents<E> {
     }
 
     /// SSZ decode with fork variant determined by slot.
-    pub fn from_ssz_bytes(bytes: &[u8], spec: &ChainSpec) -> Result<Self, ssz::DecodeError> {
+    pub fn from_ssz_bytes(bytes: &[u8], spec: &ChainSpec) -> Result<Self, DecodeError> {
         let slot_len = <Slot as Decode>::ssz_fixed_len();
         let slot_bytes = bytes
             .get(0..slot_len)
@@ -1678,10 +1678,7 @@ impl<E: EthSpec> FullBlockContents<E> {
     }
 
     /// SSZ decode with fork variant passed in explicitly.
-    pub fn from_ssz_bytes_for_fork(
-        bytes: &[u8],
-        fork_name: ForkName,
-    ) -> Result<Self, ssz::DecodeError> {
+    pub fn from_ssz_bytes_for_fork(bytes: &[u8], fork_name: ForkName) -> Result<Self, DecodeError> {
         if fork_name.deneb_enabled() {
             let mut builder = ssz::SszDecoderBuilder::new(bytes);
 
@@ -1836,7 +1833,7 @@ impl<E: EthSpec> PublishBlockRequest<E> {
     }
 
     /// SSZ decode with fork variant determined by `fork_name`.
-    pub fn from_ssz_bytes(bytes: &[u8], fork_name: ForkName) -> Result<Self, ssz::DecodeError> {
+    pub fn from_ssz_bytes(bytes: &[u8], fork_name: ForkName) -> Result<Self, DecodeError> {
         if fork_name.deneb_enabled() {
             let mut builder = ssz::SszDecoderBuilder::new(bytes);
             builder.register_anonymous_variable_length_item()?;
@@ -1845,7 +1842,7 @@ impl<E: EthSpec> PublishBlockRequest<E> {
 
             let mut decoder = builder.build()?;
             let block = decoder.decode_next_with(|bytes| {
-                SignedBeaconBlock::from_ssz_bytes_for_fork(bytes, fork_name)
+                SignedBeaconBlock::from_ssz_bytes_by_fork(bytes, fork_name)
             })?;
             let kzg_proofs = decoder.decode_next()?;
             let blobs = decoder.decode_next()?;
@@ -1854,7 +1851,7 @@ impl<E: EthSpec> PublishBlockRequest<E> {
                 Some((kzg_proofs, blobs)),
             ))
         } else {
-            SignedBeaconBlock::from_ssz_bytes_for_fork(bytes, fork_name)
+            SignedBeaconBlock::from_ssz_bytes_by_fork(bytes, fork_name)
                 .map(|block| PublishBlockRequest::Block(Arc::new(block)))
         }
     }
@@ -1946,6 +1943,24 @@ pub enum FullPayloadContents<E: EthSpec> {
     PayloadAndBlobs(ExecutionPayloadAndBlobs<E>),
 }
 
+impl<E: EthSpec> ForkVersionDecode for FullPayloadContents<E> {
+    fn from_ssz_bytes_by_fork(bytes: &[u8], fork_name: ForkName) -> Result<Self, DecodeError> {
+        if fork_name.deneb_enabled() {
+            Ok(Self::PayloadAndBlobs(
+                ExecutionPayloadAndBlobs::from_ssz_bytes_by_fork(bytes, fork_name)?,
+            ))
+        } else if fork_name.bellatrix_enabled() {
+            Ok(Self::Payload(ExecutionPayload::from_ssz_bytes_by_fork(
+                bytes, fork_name,
+            )?))
+        } else {
+            Err(ssz::DecodeError::BytesInvalid(format!(
+                "FullPayloadContents decoding for {fork_name} not implemented"
+            )))
+        }
+    }
+}
+
 impl<E: EthSpec> FullPayloadContents<E> {
     pub fn new(
         execution_payload: ExecutionPayload<E>,
@@ -2012,6 +2027,36 @@ pub struct ExecutionPayloadAndBlobs<E: EthSpec> {
     pub blobs_bundle: BlobsBundle<E>,
 }
 
+impl<E: EthSpec> ForkVersionDecode for ExecutionPayloadAndBlobs<E> {
+    fn from_ssz_bytes_by_fork(bytes: &[u8], fork_name: ForkName) -> Result<Self, DecodeError> {
+        let mut builder = ssz::SszDecoderBuilder::new(bytes);
+        builder.register_anonymous_variable_length_item()?;
+        builder.register_type::<BlobsBundle<E>>()?;
+        let mut decoder = builder.build()?;
+
+        if fork_name.deneb_enabled() {
+            let execution_payload = decoder.decode_next_with(|bytes| {
+                ExecutionPayload::from_ssz_bytes_by_fork(bytes, fork_name)
+            })?;
+            let blobs_bundle = decoder.decode_next()?;
+            Ok(Self {
+                execution_payload,
+                blobs_bundle,
+            })
+        } else {
+            Err(DecodeError::BytesInvalid(format!(
+                "ExecutionPayloadAndBlobs decoding for {fork_name} not implemented"
+            )))
+        }
+    }
+}
+
+#[derive(Debug)]
+pub enum ContentType {
+    Json,
+    Ssz,
+}
+
 #[derive(Clone, Debug, Default, PartialEq, Serialize, Deserialize, Encode, Decode)]
 #[serde(bound = "E: EthSpec")]
 pub struct BlobsBundle<E: EthSpec> {
diff --git a/consensus/types/src/builder_bid.rs b/consensus/types/src/builder_bid.rs
index ac53c41216f..49911c39095 100644
--- a/consensus/types/src/builder_bid.rs
+++ b/consensus/types/src/builder_bid.rs
@@ -3,25 +3,37 @@ use crate::{
     ChainSpec, EthSpec, ExecutionPayloadHeaderBellatrix, ExecutionPayloadHeaderCapella,
     ExecutionPayloadHeaderDeneb, ExecutionPayloadHeaderElectra, ExecutionPayloadHeaderFulu,
     ExecutionPayloadHeaderRef, ExecutionPayloadHeaderRefMut, ExecutionRequests, ForkName,
-    ForkVersionDeserialize, SignedRoot, Uint256,
+    ForkVersionDecode, ForkVersionDeserialize, SignedRoot, Uint256,
 };
 use bls::PublicKeyBytes;
 use bls::Signature;
 use serde::{Deserialize, Deserializer, Serialize};
+use ssz::Decode;
+use ssz_derive::{Decode, Encode};
 use superstruct::superstruct;
 use tree_hash_derive::TreeHash;
 
 #[superstruct(
     variants(Bellatrix, Capella, Deneb, Electra, Fulu),
     variant_attributes(
-        derive(PartialEq, Debug, Serialize, Deserialize, TreeHash, Clone),
+        derive(
+            PartialEq,
+            Debug,
+            Encode,
+            Serialize,
+            Deserialize,
+            TreeHash,
+            Decode,
+            Clone
+        ),
         serde(bound = "E: EthSpec", deny_unknown_fields)
     ),
     map_ref_into(ExecutionPayloadHeaderRef),
     map_ref_mut_into(ExecutionPayloadHeaderRefMut)
 )]
-#[derive(PartialEq, Debug, Serialize, Deserialize, TreeHash, Clone)]
+#[derive(PartialEq, Debug, Encode, Serialize, Deserialize, TreeHash, Clone)]
 #[serde(bound = "E: EthSpec", deny_unknown_fields, untagged)]
+#[ssz(enum_behaviour = "transparent")]
 #[tree_hash(enum_behaviour = "transparent")]
 pub struct BuilderBid<E: EthSpec> {
     #[superstruct(only(Bellatrix), partial_getter(rename = "header_bellatrix"))]
@@ -65,16 +77,54 @@ impl<'a, E: EthSpec> BuilderBidRefMut<'a, E> {
     }
 }
 
+impl<E: EthSpec> ForkVersionDecode for BuilderBid<E> {
+    /// SSZ decode with explicit fork variant.
+    fn from_ssz_bytes_by_fork(bytes: &[u8], fork_name: ForkName) -> Result<Self, ssz::DecodeError> {
+        let builder_bid = match fork_name {
+            ForkName::Altair | ForkName::Base => {
+                return Err(ssz::DecodeError::BytesInvalid(format!(
+                    "unsupported fork for ExecutionPayloadHeader: {fork_name}",
+                )))
+            }
+            ForkName::Bellatrix => {
+                BuilderBid::Bellatrix(BuilderBidBellatrix::from_ssz_bytes(bytes)?)
+            }
+            ForkName::Capella => BuilderBid::Capella(BuilderBidCapella::from_ssz_bytes(bytes)?),
+            ForkName::Deneb => BuilderBid::Deneb(BuilderBidDeneb::from_ssz_bytes(bytes)?),
+            ForkName::Electra => BuilderBid::Electra(BuilderBidElectra::from_ssz_bytes(bytes)?),
+            ForkName::Fulu => BuilderBid::Fulu(BuilderBidFulu::from_ssz_bytes(bytes)?),
+        };
+        Ok(builder_bid)
+    }
+}
+
 impl<E: EthSpec> SignedRoot for BuilderBid<E> {}
 
 /// Validator registration, for use in interacting with servers implementing the builder API.
-#[derive(PartialEq, Debug, Serialize, Deserialize, Clone)]
+#[derive(PartialEq, Debug, Encode, Serialize, Deserialize, Clone)]
 #[serde(bound = "E: EthSpec")]
 pub struct SignedBuilderBid<E: EthSpec> {
     pub message: BuilderBid<E>,
     pub signature: Signature,
 }
 
+impl<E: EthSpec> ForkVersionDecode for SignedBuilderBid<E> {
+    /// SSZ decode with explicit fork variant.
+    fn from_ssz_bytes_by_fork(bytes: &[u8], fork_name: ForkName) -> Result<Self, ssz::DecodeError> {
+        let mut builder = ssz::SszDecoderBuilder::new(bytes);
+
+        builder.register_anonymous_variable_length_item()?;
+        builder.register_type::<Signature>()?;
+
+        let mut decoder = builder.build()?;
+        let message = decoder
+            .decode_next_with(|bytes| BuilderBid::from_ssz_bytes_by_fork(bytes, fork_name))?;
+        let signature = decoder.decode_next()?;
+
+        Ok(Self { message, signature })
+    }
+}
+
 impl<E: EthSpec> ForkVersionDeserialize for BuilderBid<E> {
     fn deserialize_by_fork<'de, D: Deserializer<'de>>(
         value: serde_json::value::Value,
diff --git a/consensus/types/src/execution_payload.rs b/consensus/types/src/execution_payload.rs
index 2df66343af1..5d756c8529f 100644
--- a/consensus/types/src/execution_payload.rs
+++ b/consensus/types/src/execution_payload.rs
@@ -40,7 +40,7 @@ pub type Withdrawals<E> = VariableList<Withdrawal, <E as EthSpec>::MaxWithdrawal
     map_ref_into(ExecutionPayloadHeader)
 )]
 #[derive(
-    Debug, Clone, Serialize, Encode, Deserialize, TreeHash, Derivative, arbitrary::Arbitrary,
+    Debug, Clone, Serialize, Deserialize, Encode, TreeHash, Derivative, arbitrary::Arbitrary,
 )]
 #[derivative(PartialEq, Hash(bound = "E: EthSpec"))]
 #[serde(bound = "E: EthSpec", untagged)]
@@ -102,8 +102,9 @@ impl<'a, E: EthSpec> ExecutionPayloadRef<'a, E> {
     }
 }
 
-impl<E: EthSpec> ExecutionPayload<E> {
-    pub fn from_ssz_bytes(bytes: &[u8], fork_name: ForkName) -> Result<Self, ssz::DecodeError> {
+impl<E: EthSpec> ForkVersionDecode for ExecutionPayload<E> {
+    /// SSZ decode with explicit fork variant.
+    fn from_ssz_bytes_by_fork(bytes: &[u8], fork_name: ForkName) -> Result<Self, ssz::DecodeError> {
         match fork_name {
             ForkName::Base | ForkName::Altair => Err(ssz::DecodeError::BytesInvalid(format!(
                 "unsupported fork for ExecutionPayload: {fork_name}",
@@ -117,7 +118,9 @@ impl<E: EthSpec> ExecutionPayload<E> {
             ForkName::Fulu => ExecutionPayloadFulu::from_ssz_bytes(bytes).map(Self::Fulu),
         }
     }
+}
 
+impl<E: EthSpec> ExecutionPayload<E> {
     #[allow(clippy::arithmetic_side_effects)]
     /// Returns the maximum size of an execution payload.
     pub fn max_execution_payload_bellatrix_size() -> usize {
diff --git a/consensus/types/src/fork_versioned_response.rs b/consensus/types/src/fork_versioned_response.rs
index cd78b5b3ca0..7e4efd05d66 100644
--- a/consensus/types/src/fork_versioned_response.rs
+++ b/consensus/types/src/fork_versioned_response.rs
@@ -4,6 +4,11 @@ use serde::{Deserialize, Deserializer, Serialize};
 use serde_json::value::Value;
 use std::sync::Arc;
 
+pub trait ForkVersionDecode: Sized {
+    /// SSZ decode with explicit fork variant.
+    fn from_ssz_bytes_by_fork(bytes: &[u8], fork_name: ForkName) -> Result<Self, ssz::DecodeError>;
+}
+
 pub trait ForkVersionDeserialize: Sized + DeserializeOwned {
     fn deserialize_by_fork<'de, D: Deserializer<'de>>(
         value: Value,
diff --git a/consensus/types/src/lib.rs b/consensus/types/src/lib.rs
index 11d1f5271b7..73a50b4ef3e 100644
--- a/consensus/types/src/lib.rs
+++ b/consensus/types/src/lib.rs
@@ -178,7 +178,9 @@ pub use crate::fork::Fork;
 pub use crate::fork_context::ForkContext;
 pub use crate::fork_data::ForkData;
 pub use crate::fork_name::{ForkName, InconsistentFork};
-pub use crate::fork_versioned_response::{ForkVersionDeserialize, ForkVersionedResponse};
+pub use crate::fork_versioned_response::{
+    ForkVersionDecode, ForkVersionDeserialize, ForkVersionedResponse,
+};
 pub use crate::graffiti::{Graffiti, GRAFFITI_BYTES_LEN};
 pub use crate::historical_batch::HistoricalBatch;
 pub use crate::indexed_attestation::{
diff --git a/consensus/types/src/signed_beacon_block.rs b/consensus/types/src/signed_beacon_block.rs
index d9bf9bf55dd..eb5925a29b5 100644
--- a/consensus/types/src/signed_beacon_block.rs
+++ b/consensus/types/src/signed_beacon_block.rs
@@ -86,6 +86,17 @@ pub struct SignedBeaconBlock<E: EthSpec, Payload: AbstractExecPayload<E> = FullP
     pub signature: Signature,
 }
 
+impl<E: EthSpec, Payload: AbstractExecPayload<E>> ForkVersionDecode
+    for SignedBeaconBlock<E, Payload>
+{
+    /// SSZ decode with explicit fork variant.
+    fn from_ssz_bytes_by_fork(bytes: &[u8], fork_name: ForkName) -> Result<Self, ssz::DecodeError> {
+        Self::from_ssz_bytes_with(bytes, |bytes| {
+            BeaconBlock::from_ssz_bytes_for_fork(bytes, fork_name)
+        })
+    }
+}
+
 pub type SignedBlindedBeaconBlock<E> = SignedBeaconBlock<E, BlindedPayload<E>>;
 
 impl<E: EthSpec, Payload: AbstractExecPayload<E>> SignedBeaconBlock<E, Payload> {
@@ -108,16 +119,6 @@ impl<E: EthSpec, Payload: AbstractExecPayload<E>> SignedBeaconBlock<E, Payload>
         Self::from_ssz_bytes_with(bytes, |bytes| BeaconBlock::from_ssz_bytes(bytes, spec))
     }
 
-    /// SSZ decode with explicit fork variant.
-    pub fn from_ssz_bytes_for_fork(
-        bytes: &[u8],
-        fork_name: ForkName,
-    ) -> Result<Self, ssz::DecodeError> {
-        Self::from_ssz_bytes_with(bytes, |bytes| {
-            BeaconBlock::from_ssz_bytes_for_fork(bytes, fork_name)
-        })
-    }
-
     /// SSZ decode which attempts to decode all variants (slow).
     pub fn any_from_ssz_bytes(bytes: &[u8]) -> Result<Self, ssz::DecodeError> {
         Self::from_ssz_bytes_with(bytes, BeaconBlock::any_from_ssz_bytes)
diff --git a/testing/ef_tests/src/cases/operations.rs b/testing/ef_tests/src/cases/operations.rs
index adb5bee7681..7178edb151c 100644
--- a/testing/ef_tests/src/cases/operations.rs
+++ b/testing/ef_tests/src/cases/operations.rs
@@ -25,9 +25,9 @@ use std::fmt::Debug;
 use types::{
     Attestation, AttesterSlashing, BeaconBlock, BeaconBlockBody, BeaconBlockBodyBellatrix,
     BeaconBlockBodyCapella, BeaconBlockBodyDeneb, BeaconBlockBodyElectra, BeaconState,
-    BlindedPayload, ConsolidationRequest, Deposit, DepositRequest, ExecutionPayload, FullPayload,
-    ProposerSlashing, SignedBlsToExecutionChange, SignedVoluntaryExit, SyncAggregate,
-    WithdrawalRequest,
+    BlindedPayload, ConsolidationRequest, Deposit, DepositRequest, ExecutionPayload,
+    ForkVersionDecode, FullPayload, ProposerSlashing, SignedBlsToExecutionChange,
+    SignedVoluntaryExit, SyncAggregate, WithdrawalRequest,
 };
 
 #[derive(Debug, Clone, Default, Deserialize)]
@@ -398,7 +398,7 @@ impl<E: EthSpec> Operation<E> for WithdrawalsPayload<E> {
 
     fn decode(path: &Path, fork_name: ForkName, _spec: &ChainSpec) -> Result<Self, Error> {
         ssz_decode_file_with(path, |bytes| {
-            ExecutionPayload::from_ssz_bytes(bytes, fork_name)
+            ExecutionPayload::from_ssz_bytes_by_fork(bytes, fork_name)
         })
         .map(|payload| WithdrawalsPayload {
             payload: payload.into(),