diff --git a/google/cloud/aiplatform/v1/reasoning_engine.proto b/google/cloud/aiplatform/v1/reasoning_engine.proto
index 80c8b3bad9..585c9c864f 100644
--- a/google/cloud/aiplatform/v1/reasoning_engine.proto
+++ b/google/cloud/aiplatform/v1/reasoning_engine.proto
@@ -226,6 +226,25 @@ message ReasoningEngineSpec {
     AGENT_IDENTITY = 3;
   }
 
+  // Specification for building container image.
+  message BuildSpec {
+    // Optional. The resource name of the Cloud Build WorkerPool to use for
+    // the build.
+    // Format:
+    // `projects/{project}/locations/{location}/workerPools/{worker_pool}`
+    string worker_pool = 1 [(google.api.field_behavior) = OPTIONAL];
+
+    // Optional. The service account that Cloud Build uses to run the build.
+    //
+    // This field is only applicable when `worker_pool` is specified (i.e., for
+    // custom worker pools). If `worker_pool` is not specified, this field is
+    // ignored and the build runs using the Google-managed service agent.
+    //
+    // Format: `projects/{project}/serviceAccounts/{service_account}` or
+    // `{service_account}@{project}.iam.gserviceaccount.com`
+    string service_account = 2 [(google.api.field_behavior) = OPTIONAL];
+  }
+
   // Defines the source for the deployment.
   // The `package_spec` field should not be set if `deployment_source` is
   // specified.
@@ -270,6 +289,9 @@ message ReasoningEngineSpec {
   // default Vertex AI Reasoning Engine Service Agent in the project will be
   // used.
   IdentityType identity_type = 12 [(google.api.field_behavior) = OPTIONAL];
+
+  // Optional. Configuration for building container image.
+  BuildSpec build_spec = 16 [(google.api.field_behavior) = OPTIONAL];
 }
 
 // ReasoningEngine provides a customizable runtime for models to determine
diff --git a/google/cloud/aiplatform/v1beta1/reasoning_engine.proto b/google/cloud/aiplatform/v1beta1/reasoning_engine.proto
index 919beef371..ca45a85af2 100644
--- a/google/cloud/aiplatform/v1beta1/reasoning_engine.proto
+++ b/google/cloud/aiplatform/v1beta1/reasoning_engine.proto
@@ -228,6 +228,25 @@ message ReasoningEngineSpec {
     AGENT_IDENTITY = 3;
   }
 
+  // Specification for building container image.
+  message BuildSpec {
+    // Optional. The resource name of the Cloud Build WorkerPool to use for
+    // the build.
+    // Format:
+    // `projects/{project}/locations/{location}/workerPools/{worker_pool}`
+    string worker_pool = 1 [(google.api.field_behavior) = OPTIONAL];
+
+    // Optional. The service account that Cloud Build uses to run the build.
+    //
+    // This field is only applicable when `worker_pool` is specified (i.e., for
+    // custom worker pools). If `worker_pool` is not specified, this field is
+    // ignored and the build runs using the Google-managed service agent.
+    //
+    // Format: `projects/{project}/serviceAccounts/{service_account}` or
+    // `{service_account}@{project}.iam.gserviceaccount.com`
+    string service_account = 2 [(google.api.field_behavior) = OPTIONAL];
+  }
+
   // Defines the source for the deployment.
   // The `package_spec` field should not be set if `deployment_source` is
   // specified.
@@ -272,6 +291,9 @@ message ReasoningEngineSpec {
   // default Vertex AI Reasoning Engine Service Agent in the project will be
   // used.
   IdentityType identity_type = 12 [(google.api.field_behavior) = OPTIONAL];
+
+  // Optional. Configuration for building container image.
+  BuildSpec build_spec = 16 [(google.api.field_behavior) = OPTIONAL];
 }
 
 // ReasoningEngine provides a customizable runtime for models to determine