diff --git a/extensions/openai/embedding-provider.test.ts b/extensions/openai/embedding-provider.test.ts
index 2d5f364b186..6afebd552c9 100644
--- a/extensions/openai/embedding-provider.test.ts
+++ b/extensions/openai/embedding-provider.test.ts
@@ -85,4 +85,22 @@ describe("OpenAI embedding provider", () => {
       }),
     );
   });
+
+  it("sends outputDimensionality as OpenAI dimensions", async () => {
+    const { provider } = await createOpenAiEmbeddingProvider(
+      createOptions({ outputDimensionality: 512 }),
+    );
+
+    await provider.embedBatch(["doc"]);
+
+    expect(mocks.fetchRemoteEmbeddingVectors).toHaveBeenCalledWith(
+      expect.objectContaining({
+        body: {
+          model: "text-embedding-3-small",
+          input: ["doc"],
+          dimensions: 512,
+        },
+      }),
+    );
+  });
 });
diff --git a/extensions/openai/embedding-provider.ts b/extensions/openai/embedding-provider.ts
index 94a30383541..c5ebaab4946 100644
--- a/extensions/openai/embedding-provider.ts
+++ b/extensions/openai/embedding-provider.ts
@@ -16,6 +16,7 @@ export type OpenAiEmbeddingClient = {
   inputType?: string;
   queryInputType?: string;
   documentInputType?: string;
+  outputDimensionality?: number;
 };
 
 const DEFAULT_OPENAI_BASE_URL = "https://api.openai.com/v1";
@@ -59,6 +60,9 @@ export async function createOpenAiEmbeddingProvider(
       body: {
         model: client.model,
         input,
+        ...(typeof client.outputDimensionality === "number"
+          ? { dimensions: client.outputDimensionality }
+          : {}),
         ...(inputType ? { input_type: inputType } : {}),
       },
       errorPrefix: "openai embeddings failed",
@@ -96,5 +100,6 @@ async function resolveOpenAiEmbeddingClient(
     inputType: options.inputType,
     queryInputType: options.queryInputType,
     documentInputType: options.documentInputType,
+    outputDimensionality: options.outputDimensionality,
   };
 }
diff --git a/extensions/openai/memory-embedding-adapter.test.ts b/extensions/openai/memory-embedding-adapter.test.ts
index 2cdc26d4742..a4fb3f3c0b9 100644
--- a/extensions/openai/memory-embedding-adapter.test.ts
+++ b/extensions/openai/memory-embedding-adapter.test.ts
@@ -37,6 +37,7 @@ describe("OpenAI memory embedding adapter", () => {
         model: "text-embedding-3-small",
         inputType: "passage",
         documentInputType: "document",
+        outputDimensionality: 512,
       },
     });
   });
@@ -66,6 +67,7 @@ describe("OpenAI memory embedding adapter", () => {
             body: {
               model: "text-embedding-3-small",
               input: "doc one",
+              dimensions: 512,
               input_type: "document",
             },
           }),
diff --git a/extensions/openai/memory-embedding-adapter.ts b/extensions/openai/memory-embedding-adapter.ts
index b592b6c005b..a9a0474122f 100644
--- a/extensions/openai/memory-embedding-adapter.ts
+++ b/extensions/openai/memory-embedding-adapter.ts
@@ -32,6 +32,7 @@ export const openAiMemoryEmbeddingProviderAdapter: MemoryEmbeddingProviderAdapte
           provider: "openai",
           baseUrl: client.baseUrl,
           model: client.model,
+          outputDimensionality: client.outputDimensionality,
           documentInputType: client.documentInputType ?? client.inputType,
           headers: sanitizeEmbeddingCacheHeaders(client.headers, ["authorization"]),
         },
@@ -47,6 +48,9 @@ export const openAiMemoryEmbeddingProviderAdapter: MemoryEmbeddingProviderAdapte
               body: {
                 model: client.model,
                 input: chunk.text,
+                ...(typeof client.outputDimensionality === "number"
+                  ? { dimensions: client.outputDimensionality }
+                  : {}),
                 ...(inputType ? { input_type: inputType } : {}),
               },
             })),