diff --git a/openapi/openapiv2.json b/openapi/openapiv2.json
index 08db7afbf..cc20985af 100644
--- a/openapi/openapiv2.json
+++ b/openapi/openapiv2.json
@@ -19063,7 +19063,8 @@
       "enum": [
         "START_CHILD_WORKFLOW_EXECUTION_FAILED_CAUSE_UNSPECIFIED",
         "START_CHILD_WORKFLOW_EXECUTION_FAILED_CAUSE_WORKFLOW_ALREADY_EXISTS",
-        "START_CHILD_WORKFLOW_EXECUTION_FAILED_CAUSE_NAMESPACE_NOT_FOUND"
+        "START_CHILD_WORKFLOW_EXECUTION_FAILED_CAUSE_NAMESPACE_NOT_FOUND",
+        "START_CHILD_WORKFLOW_EXECUTION_FAILED_CAUSE_INVALID_VERSIONING_OVERRIDE"
       ],
       "default": "START_CHILD_WORKFLOW_EXECUTION_FAILED_CAUSE_UNSPECIFIED"
     },
@@ -19181,6 +19182,10 @@
           "$ref": "#/definitions/v1TimeSkippingConfig",
           "description": "The propagated time-skipping configuration for the child workflow."
         },
+        "versioningOverride": {
+          "$ref": "#/definitions/v1VersioningOverride",
+          "description": "Versioning override requested for the child workflow. If present, this explicit override\ntakes precedence over versioning behavior inherited from the parent workflow."
+        },
         "initialSkippedDuration": {
           "type": "string",
           "description": "Propagate the duration skipped to the child workflow."
diff --git a/openapi/openapiv3.yaml b/openapi/openapiv3.yaml
index bd6bb404c..43bfe9e59 100644
--- a/openapi/openapiv3.yaml
+++ b/openapi/openapiv3.yaml
@@ -16561,6 +16561,7 @@ components:
             - START_CHILD_WORKFLOW_EXECUTION_FAILED_CAUSE_UNSPECIFIED
             - START_CHILD_WORKFLOW_EXECUTION_FAILED_CAUSE_WORKFLOW_ALREADY_EXISTS
             - START_CHILD_WORKFLOW_EXECUTION_FAILED_CAUSE_NAMESPACE_NOT_FOUND
+            - START_CHILD_WORKFLOW_EXECUTION_FAILED_CAUSE_INVALID_VERSIONING_OVERRIDE
           type: string
           format: enum
         control:
@@ -16652,6 +16653,12 @@ components:
           allOf:
             - $ref: '#/components/schemas/TimeSkippingConfig'
           description: The propagated time-skipping configuration for the child workflow.
+        versioningOverride:
+          allOf:
+            - $ref: '#/components/schemas/VersioningOverride'
+          description: |-
+            Versioning override requested for the child workflow. If present, this explicit override
+             takes precedence over versioning behavior inherited from the parent workflow.
         initialSkippedDuration:
           pattern: ^-?(?:0|[1-9][0-9]{0,11})(?:\.[0-9]{1,9})?s$
           type: string
diff --git a/temporal/api/command/v1/message.proto b/temporal/api/command/v1/message.proto
index 2ce183aad..ee839115b 100644
--- a/temporal/api/command/v1/message.proto
+++ b/temporal/api/command/v1/message.proto
@@ -16,6 +16,7 @@ import "temporal/api/enums/v1/command_type.proto";
 import "temporal/api/common/v1/message.proto";
 import "temporal/api/failure/v1/message.proto";
 import "temporal/api/taskqueue/v1/message.proto";
+import "temporal/api/workflow/v1/message.proto";
 import "temporal/api/sdk/v1/user_metadata.proto";
 import "temporal/api/sdk/v1/event_group_marker.proto";
 
@@ -221,6 +222,9 @@ message StartChildWorkflowExecutionCommandAttributes {
     // Priority metadata. If this message is not present, or any fields are not
     // present, they inherit the values from the workflow.
     temporal.api.common.v1.Priority priority = 18;
+    // Versioning override for the child workflow. If present, this explicit override takes
+    // precedence over versioning behavior inherited from the parent workflow.
+    temporal.api.workflow.v1.VersioningOverride versioning_override = 19;
 }
 
 message ProtocolMessageCommandAttributes {
diff --git a/temporal/api/enums/v1/failed_cause.proto b/temporal/api/enums/v1/failed_cause.proto
index 6b3eedfce..1085f4e45 100644
--- a/temporal/api/enums/v1/failed_cause.proto
+++ b/temporal/api/enums/v1/failed_cause.proto
@@ -89,6 +89,7 @@ enum StartChildWorkflowExecutionFailedCause {
     START_CHILD_WORKFLOW_EXECUTION_FAILED_CAUSE_UNSPECIFIED = 0;
     START_CHILD_WORKFLOW_EXECUTION_FAILED_CAUSE_WORKFLOW_ALREADY_EXISTS = 1;
     START_CHILD_WORKFLOW_EXECUTION_FAILED_CAUSE_NAMESPACE_NOT_FOUND = 2;
+    START_CHILD_WORKFLOW_EXECUTION_FAILED_CAUSE_INVALID_VERSIONING_OVERRIDE = 3;
 }
 
 enum CancelExternalWorkflowExecutionFailedCause {
@@ -136,4 +137,3 @@ enum ResourceExhaustedScope {
     // Exhausted resource is a namespace-level resource.
     RESOURCE_EXHAUSTED_SCOPE_SYSTEM = 2;
 }
-
diff --git a/temporal/api/history/v1/message.proto b/temporal/api/history/v1/message.proto
index 32f4f83cc..56cb77f83 100644
--- a/temporal/api/history/v1/message.proto
+++ b/temporal/api/history/v1/message.proto
@@ -779,6 +779,10 @@ message StartChildWorkflowExecutionInitiatedEventAttributes {
     // The propagated time-skipping configuration for the child workflow.
     temporal.api.workflow.v1.TimeSkippingConfig time_skipping_config = 21;
 
+    // Versioning override requested for the child workflow. If present, this explicit override
+    // takes precedence over versioning behavior inherited from the parent workflow.
+    temporal.api.workflow.v1.VersioningOverride versioning_override = 22;
+
     // Propagate the duration skipped to the child workflow.
     google.protobuf.Duration initial_skipped_duration = 30;
 }