diff --git a/packages/core/src/submodules/client/index.ts b/packages/core/src/submodules/client/index.ts
index 1a2cc9d139ff..492c6cdda988 100644
--- a/packages/core/src/submodules/client/index.ts
+++ b/packages/core/src/submodules/client/index.ts
@@ -1,3 +1,4 @@
 export * from "./emitWarningIfUnsupportedVersion";
 export * from "./setCredentialFeature";
 export * from "./setFeature";
+export * from "./setTokenFeature";
diff --git a/packages/core/src/submodules/client/setTokenFeature.spec.ts b/packages/core/src/submodules/client/setTokenFeature.spec.ts
new file mode 100644
index 000000000000..08424ec6ba4a
--- /dev/null
+++ b/packages/core/src/submodules/client/setTokenFeature.spec.ts
@@ -0,0 +1,17 @@
+import { AttributedTokenIdentity } from "@aws-sdk/types";
+import { describe, expect, test as it } from "vitest";
+
+import { setTokenFeature } from "./setTokenFeature";
+
+describe(setTokenFeature.name, () => {
+  it("should create the data path if it does't exist", () => {
+    const token = { token: "" } as AttributedTokenIdentity;
+
+    expect(setTokenFeature(token, "BEARER_SERVICE_ENV_VARS", "3")).toEqual({
+      token: "",
+      $source: {
+        BEARER_SERVICE_ENV_VARS: "3",
+      },
+    });
+  });
+});
diff --git a/packages/core/src/submodules/client/setTokenFeature.ts b/packages/core/src/submodules/client/setTokenFeature.ts
new file mode 100644
index 000000000000..b22e64c9d65e
--- /dev/null
+++ b/packages/core/src/submodules/client/setTokenFeature.ts
@@ -0,0 +1,18 @@
+import type { AttributedTokenIdentity, AwsSdkTokenFeatures } from "@aws-sdk/types";
+
+/**
+ * @internal
+ *
+ * @returns the token with source feature attribution.
+ */
+export function setTokenFeature<F extends keyof AwsSdkTokenFeatures>(
+  token: AttributedTokenIdentity,
+  feature: F,
+  value: AwsSdkTokenFeatures[F]
+): AttributedTokenIdentity {
+  if (!token.$source) {
+    token.$source = {};
+  }
+  token.$source![feature] = value;
+  return token;
+}
diff --git a/packages/token-providers/src/fromEnvSigningName.spec.ts b/packages/token-providers/src/fromEnvSigningName.spec.ts
index f570dfedba78..856c391f1af9 100644
--- a/packages/token-providers/src/fromEnvSigningName.spec.ts
+++ b/packages/token-providers/src/fromEnvSigningName.spec.ts
@@ -1,9 +1,9 @@
-import { getBearerTokenEnvKey } from "@aws-sdk/core";
+import { getBearerTokenEnvKey } from "@aws-sdk/core/httpAuthSchemes";
 import { afterEach, beforeEach, describe, expect, it, vi } from "vitest";
 
 import { fromEnvSigningName } from "./fromEnvSigningName";
 
-vi.mock("@aws-sdk/core");
+vi.mock("@aws-sdk/core/httpAuthSchemes");
 
 describe(fromEnvSigningName.name, () => {
   const originalEnv = process.env;
@@ -40,7 +40,12 @@ describe(fromEnvSigningName.name, () => {
     const mockBearerToken = "mock-bearer-token";
     process.env[mockBearerTokenEnvKey] = mockBearerToken;
     const token = await fromEnvSigningName(mockInit)();
-    expect(token).toEqual({ token: mockBearerToken });
+    expect(token).toEqual({
+      token: mockBearerToken,
+      $source: {
+        BEARER_SERVICE_ENV_VARS: "3",
+      },
+    });
     expect(getBearerTokenEnvKey).toHaveBeenCalledWith(mockInit.signingName);
   });
 });
diff --git a/packages/token-providers/src/fromEnvSigningName.ts b/packages/token-providers/src/fromEnvSigningName.ts
index c0a358bbaeed..a53939919f47 100644
--- a/packages/token-providers/src/fromEnvSigningName.ts
+++ b/packages/token-providers/src/fromEnvSigningName.ts
@@ -1,5 +1,6 @@
-import { getBearerTokenEnvKey } from "@aws-sdk/core";
-import type { CredentialProviderOptions, TokenIdentityProvider } from "@aws-sdk/types";
+import { setTokenFeature } from "@aws-sdk/core/client";
+import { getBearerTokenEnvKey } from "@aws-sdk/core/httpAuthSchemes";
+import type { AttributedTokenIdentity, CredentialProviderOptions, TokenIdentityProvider } from "@aws-sdk/types";
 import { TokenProviderError } from "@smithy/property-provider";
 
 /**
@@ -33,5 +34,8 @@ export const fromEnvSigningName =
       throw new TokenProviderError(`Token not present in '${bearerTokenKey}' environment variable`, { logger });
     }
 
-    return { token: process.env[bearerTokenKey]! };
+    const token = { token: process.env[bearerTokenKey]! } as AttributedTokenIdentity;
+    setTokenFeature(token, "BEARER_SERVICE_ENV_VARS", "3");
+
+    return token;
   };
diff --git a/packages/types/src/feature-ids.ts b/packages/types/src/feature-ids.ts
index 6464a693651b..a62c25811a33 100644
--- a/packages/types/src/feature-ids.ts
+++ b/packages/types/src/feature-ids.ts
@@ -32,7 +32,8 @@ export type AwsSdkFeatures = Partial<{
   FLEXIBLE_CHECKSUMS_RES_WHEN_REQUIRED: "c";
   DDB_MAPPER: "d";
 }> &
-  AwsSdkCredentialsFeatures;
+  AwsSdkCredentialsFeatures &
+  AwsSdkTokenFeatures;
 
 /**
  * @internal
@@ -62,3 +63,10 @@ export type AwsSdkCredentialsFeatures = Partial<{
   CREDENTIALS_HTTP: "z";
   CREDENTIALS_IMDS: "0";
 }>;
+
+/**
+ * @internal
+ */
+export type AwsSdkTokenFeatures = Partial<{
+  BEARER_SERVICE_ENV_VARS: "3";
+}>;
diff --git a/packages/types/src/identity/TokenIdentity.ts b/packages/types/src/identity/TokenIdentity.ts
index 66301bc706c5..0b60067d15da 100644
--- a/packages/types/src/identity/TokenIdentity.ts
+++ b/packages/types/src/identity/TokenIdentity.ts
@@ -1 +1,13 @@
+import type { TokenIdentity } from "@smithy/types";
+
+import type { AwsSdkTokenFeatures } from "../feature-ids";
 export { TokenIdentity, TokenIdentityProvider } from "@smithy/types";
+
+/**
+ * @public
+ *
+ * TokenIdentity with source attribution metadata.
+ */
+export type AttributedTokenIdentity = TokenIdentity & {
+  $source?: AwsSdkTokenFeatures;
+};