diff --git a/temporalio/contrib/openai_agents/__init__.py b/temporalio/contrib/openai_agents/__init__.py
index 998cf61eb..2d9777aa8 100644
--- a/temporalio/contrib/openai_agents/__init__.py
+++ b/temporalio/contrib/openai_agents/__init__.py
@@ -11,6 +11,7 @@
 from temporalio.contrib.openai_agents._model_parameters import ModelActivityParameters
 from temporalio.contrib.openai_agents._temporal_openai_agents import (
     OpenAIAgentsPlugin,
+    OpenAIPayloadConverter,
     TestModel,
     TestModelProvider,
 )
@@ -23,9 +24,10 @@
 
 __all__ = [
     "AgentsWorkflowError",
-    "OpenAIAgentsPlugin",
     "ModelActivityParameters",
-    "workflow",
+    "OpenAIAgentsPlugin",
+    "OpenAIPayloadConverter",
     "TestModel",
     "TestModelProvider",
+    "workflow",
 ]
diff --git a/temporalio/contrib/openai_agents/_temporal_openai_agents.py b/temporalio/contrib/openai_agents/_temporal_openai_agents.py
index f553725cf..f8b8999a2 100644
--- a/temporalio/contrib/openai_agents/_temporal_openai_agents.py
+++ b/temporalio/contrib/openai_agents/_temporal_openai_agents.py
@@ -1,5 +1,6 @@
 """Initialize Temporal OpenAI Agents overrides."""
 
+import dataclasses
 from contextlib import asynccontextmanager, contextmanager
 from datetime import timedelta
 from typing import AsyncIterator, Callable, Optional, Union
@@ -43,6 +44,7 @@
 )
 from temporalio.converter import (
     DataConverter,
+    DefaultPayloadConverter,
 )
 from temporalio.worker import (
     Replayer,
@@ -148,8 +150,11 @@ def stream_response(
         raise NotImplementedError()
 
 
-class _OpenAIPayloadConverter(PydanticPayloadConverter):
+class OpenAIPayloadConverter(PydanticPayloadConverter):
+    """PayloadConverter for OpenAI agents."""
+
     def __init__(self) -> None:
+        """Initialize a payload converter."""
         super().__init__(ToJsonOptions(exclude_unset=True))
 
 
@@ -250,6 +255,20 @@ def init_worker_plugin(self, next: temporalio.worker.Plugin) -> None:
         """Set the next worker plugin"""
         self.next_worker_plugin = next
 
+    @staticmethod
+    def _data_converter(converter: Optional[DataConverter]) -> DataConverter:
+        if converter is None:
+            return DataConverter(payload_converter_class=OpenAIPayloadConverter)
+        elif converter.payload_converter_class is DefaultPayloadConverter:
+            return dataclasses.replace(
+                converter, payload_converter_class=OpenAIPayloadConverter
+            )
+        elif not isinstance(converter.payload_converter, OpenAIPayloadConverter):
+            raise ValueError(
+                "The payload converter must be of type OpenAIPayloadConverter."
+            )
+        return converter
+
     def configure_client(self, config: ClientConfig) -> ClientConfig:
         """Configure the Temporal client for OpenAI agents integration.
 
@@ -262,9 +281,7 @@ def configure_client(self, config: ClientConfig) -> ClientConfig:
         Returns:
             The modified client configuration.
         """
-        config["data_converter"] = DataConverter(
-            payload_converter_class=_OpenAIPayloadConverter
-        )
+        config["data_converter"] = self._data_converter(config["data_converter"])
         return self.next_client_plugin.configure_client(config)
 
     def configure_worker(self, config: WorkerConfig) -> WorkerConfig:
@@ -310,9 +327,7 @@ def configure_replayer(self, config: ReplayerConfig) -> ReplayerConfig:
         config["interceptors"] = list(config.get("interceptors") or []) + [
             OpenAIAgentsTracingInterceptor()
         ]
-        config["data_converter"] = DataConverter(
-            payload_converter_class=_OpenAIPayloadConverter
-        )
+        config["data_converter"] = self._data_converter(config.get("data_converter"))
         return self.next_worker_plugin.configure_replayer(config)
 
     @asynccontextmanager