diff --git a/api/controllers/console/app/workflow_app_log.py b/api/controllers/console/app/workflow_app_log.py
index c9bf48103b..1a2599604d 100644
--- a/api/controllers/console/app/workflow_app_log.py
+++ b/api/controllers/console/app/workflow_app_log.py
@@ -139,6 +139,11 @@ class WorkflowAppLogPartialResponse(ResponseModel):
             return int(value.timestamp())
         return value
 
+    @field_validator("evaluation", mode="before")
+    @classmethod
+    def _normalize_evaluation(cls, value: Any) -> list[dict[str, Any]] | list[WorkflowAppLogEvaluationItemResponse]:
+        return value or []
+
 
 class WorkflowArchivedLogPartialResponse(ResponseModel):
     id: str
diff --git a/api/controllers/service_api/app/workflow.py b/api/controllers/service_api/app/workflow.py
index f489bb1f4a..24c729d185 100644
--- a/api/controllers/service_api/app/workflow.py
+++ b/api/controllers/service_api/app/workflow.py
@@ -174,6 +174,11 @@ class WorkflowAppLogPartialResponse(ResponseModel):
     def _normalize_timestamp(cls, value: datetime | int | None) -> int | None:
         return _to_timestamp(value)
 
+    @field_validator("evaluation", mode="before")
+    @classmethod
+    def _normalize_evaluation(cls, value: Any) -> list[dict[str, Any]] | list[WorkflowAppLogEvaluationItemResponse]:
+        return value or []
+
 
 class WorkflowAppLogPaginationResponse(ResponseModel):
     page: int
diff --git a/api/fields/workflow_app_log_fields.py b/api/fields/workflow_app_log_fields.py
index 689e3c30c6..a5eb12e468 100644
--- a/api/fields/workflow_app_log_fields.py
+++ b/api/fields/workflow_app_log_fields.py
@@ -136,6 +136,11 @@ class WorkflowAppLogPartialResponse(ResponseModel):
     def _normalize_timestamp(cls, value: datetime | int | None) -> int | None:
         return _to_timestamp(value)
 
+    @field_validator("evaluation", mode="before")
+    @classmethod
+    def _normalize_evaluation(cls, value: Any) -> list[dict[str, Any]] | list[WorkflowAppLogEvaluationItemResponse]:
+        return value or []
+
 
 class WorkflowArchivedLogPartialResponse(ResponseModel):
     id: str
diff --git a/api/services/workflow_app_service.py b/api/services/workflow_app_service.py
index d2d6c7a92c..995c301e3f 100644
--- a/api/services/workflow_app_service.py
+++ b/api/services/workflow_app_service.py
@@ -24,6 +24,8 @@ class LogView:
 
     - Exposes `details_` for marshalling to `details` in API response
     - Exposes `evaluation_` for marshalling evaluation metrics in API response
+    - Normalizes missing evaluation results to an empty list because the API
+      schema treats "no evaluation data" as an empty collection, not `null`
     - Proxies all other attributes to the underlying `WorkflowAppLog`
     """
 
@@ -35,14 +37,14 @@ class LogView:
     ):
         self.log = log
         self.details_ = details
-        self.evaluation_ = evaluation
+        self.evaluation_ = evaluation or []
 
     @property
     def details(self) -> LogViewDetails | None:
         return self.details_
 
     @property
-    def evaluation(self) -> list[dict] | None:
+    def evaluation(self) -> list[dict]:
         return self.evaluation_
 
     def __getattr__(self, name):
@@ -192,7 +194,7 @@ class WorkflowAppService:
         eval_map = self._batch_query_evaluation_metrics(session, workflow_run_ids)
 
         items = [
-            LogView(log, details, evaluation=eval_map.get(log.workflow_run_id))
+            LogView(log, details, evaluation=eval_map.get(log.workflow_run_id, []))
             for log, details in logs_with_details
         ]
         return {
diff --git a/api/tests/unit_tests/controllers/console/app/test_workflow_app_log_api.py b/api/tests/unit_tests/controllers/console/app/test_workflow_app_log_api.py
index fa3830ada4..3dc94bae59 100644
--- a/api/tests/unit_tests/controllers/console/app/test_workflow_app_log_api.py
+++ b/api/tests/unit_tests/controllers/console/app/test_workflow_app_log_api.py
@@ -65,6 +65,25 @@ def test_workflow_app_log_pagination_response_normalizes_nested_fields():
     assert response["data"][0]["evaluation"][0]["nodeInfo"]["node_id"] == "node-1"
 
 
+def test_workflow_app_log_pagination_response_normalizes_null_evaluation_to_empty_list():
+    response = workflow_app_log_module.WorkflowAppLogPaginationResponse.model_validate(
+        {
+            "page": 1,
+            "limit": 20,
+            "total": 1,
+            "has_more": False,
+            "data": [
+                {
+                    "id": "log-1",
+                    "evaluation": None,
+                }
+            ],
+        }
+    ).model_dump(mode="json")
+
+    assert response["data"][0]["evaluation"] == []
+
+
 def test_workflow_archived_log_pagination_response_normalizes_nested_fields():
     created_at = datetime(2026, 1, 2, 3, 4, 5, tzinfo=UTC)
     response = workflow_app_log_module.WorkflowArchivedLogPaginationResponse.model_validate(
diff --git a/api/tests/unit_tests/controllers/service_api/app/test_workflow.py b/api/tests/unit_tests/controllers/service_api/app/test_workflow.py
index 74a3c75839..d883d2d2b9 100644
--- a/api/tests/unit_tests/controllers/service_api/app/test_workflow.py
+++ b/api/tests/unit_tests/controllers/service_api/app/test_workflow.py
@@ -29,6 +29,7 @@ from controllers.service_api.app.workflow import (
     DifyAPIRepositoryFactory,
     GraphEngineManager,
     WorkflowAppLogApi,
+    WorkflowAppLogPaginationResponse,
     WorkflowLogQuery,
     WorkflowRunApi,
     WorkflowRunByIdApi,
@@ -238,6 +239,25 @@ class TestWorkflowAppService:
         assert result.limit == 20
 
 
+def test_workflow_app_log_pagination_response_normalizes_null_evaluation_to_empty_list():
+    response = WorkflowAppLogPaginationResponse.model_validate(
+        {
+            "page": 1,
+            "limit": 20,
+            "total": 1,
+            "has_more": False,
+            "data": [
+                {
+                    "id": "log-1",
+                    "evaluation": None,
+                }
+            ],
+        }
+    ).model_dump(mode="json")
+
+    assert response["data"][0]["evaluation"] == []
+
+
 class TestWorkflowExecutionStatus:
     """Test WorkflowExecutionStatus enum."""