diff --git a/MdeModulePkg/Universal/Variable/RuntimeDxe/VariableSmmRuntimeDxe.c b/MdeModulePkg/Universal/Variable/RuntimeDxe/VariableSmmRuntimeDxe.c
index 3a87298160..0e0a7c5c3b 100644
--- a/MdeModulePkg/Universal/Variable/RuntimeDxe/VariableSmmRuntimeDxe.c
+++ b/MdeModulePkg/Universal/Variable/RuntimeDxe/VariableSmmRuntimeDxe.c
@@ -997,6 +997,7 @@ VariableSmmRuntimeInitialize (
   VOID                                      *SmmVariableWriteRegistration;
   EFI_EVENT                                 OnReadyToBootEvent;
   EFI_EVENT                                 ExitBootServiceEvent;
+  EFI_EVENT                                 LegacyBootEvent;
 
   EfiInitializeLock (&mVariableServicesLock, TPL_NOTIFY);
 
@@ -1064,6 +1065,17 @@ VariableSmmRuntimeInitialize (
          &ExitBootServiceEvent
          ); 
 
+  //
+  // Register the event to inform SMM variable that it is at runtime for legacy boot.
+  // Reuse OnExitBootServices() here.
+  //
+  EfiCreateEventLegacyBootEx(
+    TPL_NOTIFY,
+    OnExitBootServices,
+    NULL,
+    &LegacyBootEvent
+    );
+
   //
   // Register the event to convert the pointer for runtime.
   //