diff --git a/agentplatform/_genai/sandbox_templates.py b/agentplatform/_genai/sandbox_templates.py
index 557cd7411e..a503195be4 100644
--- a/agentplatform/_genai/sandbox_templates.py
+++ b/agentplatform/_genai/sandbox_templates.py
@@ -79,7 +79,7 @@ def _CreateSandboxEnvironmentTemplateRequestParameters_to_vertex(
         )
 
     if getv(from_object, ["display_name"]) is not None:
-        setv(parent_object, ["displayName"], getv(from_object, ["display_name"]))
+        setv(to_object, ["displayName"], getv(from_object, ["display_name"]))
 
     return to_object
 
diff --git a/tests/unit/agentplatform/genai/replays/test_ae_sandbox_templates_byoc_create.py b/tests/unit/agentplatform/genai/replays/test_ae_sandbox_templates_byoc_create.py
index 47d686b972..30ec57efb4 100644
--- a/tests/unit/agentplatform/genai/replays/test_ae_sandbox_templates_byoc_create.py
+++ b/tests/unit/agentplatform/genai/replays/test_ae_sandbox_templates_byoc_create.py
@@ -59,6 +59,18 @@ def test_sandbox_templates_byoc_create(client):
         sandbox_template_operation, types.SandboxEnvironmentTemplateOperation
     )
 
+    # Verify display_name is sent in the create request body. The replay client
+    # asserts the SDK's actual request matches this recorded request, so checking
+    # the recorded body confirms display_name is included rather than dropped
+    # (the behavior this CL fixes). interactions[0] is the create POST; later
+    # interactions are the operation polls from create() waiting on the LRO.
+    client._api_client._initialize_replay_session_if_not_loaded()
+    if client._api_client.replay_session:
+        create_request_body = client._api_client.replay_session.interactions[
+            0
+        ].request.body_segments[0]
+        assert create_request_body["displayName"] == "Test Sandbox Template 1"
+
 
 pytestmark = pytest_helper.setup(
     file=__file__,
diff --git a/tests/unit/agentplatform/genai/replays/test_ae_sandbox_templates_default_create.py b/tests/unit/agentplatform/genai/replays/test_ae_sandbox_templates_default_create.py
index f1356297ad..60087195dc 100644
--- a/tests/unit/agentplatform/genai/replays/test_ae_sandbox_templates_default_create.py
+++ b/tests/unit/agentplatform/genai/replays/test_ae_sandbox_templates_default_create.py
@@ -38,6 +38,17 @@ def test_sandbox_templates_default_create(client):
         sandbox_template_operation, types.SandboxEnvironmentTemplateOperation
     )
 
+    # Verify display_name is sent in the create request body. The replay client
+    # asserts the SDK's actual request matches this recorded request, so checking
+    # the recorded body confirms display_name is included rather than dropped
+    # (the behavior this CL fixes).
+    client._api_client._initialize_replay_session_if_not_loaded()
+    if client._api_client.replay_session:
+        create_request_body = client._api_client.replay_session.interactions[
+            0
+        ].request.body_segments[0]
+        assert create_request_body["displayName"] == "Test Sandbox Template 1"
+
 
 pytestmark = pytest_helper.setup(
     file=__file__,