diff --git a/sdks/java/harness/src/main/java/org/apache/beam/fn/harness/FnApiDoFnRunner.java b/sdks/java/harness/src/main/java/org/apache/beam/fn/harness/FnApiDoFnRunner.java
index e264fa14788a..21e79a75b45f 100644
--- a/sdks/java/harness/src/main/java/org/apache/beam/fn/harness/FnApiDoFnRunner.java
+++ b/sdks/java/harness/src/main/java/org/apache/beam/fn/harness/FnApiDoFnRunner.java
@@ -1533,6 +1533,8 @@ private <K> void processTimerDirect(
     currentTimer = timer;
     currentTimeDomain = timeDomain;
     doFnInvoker.invokeOnTimer(timerId, timerFamilyId, onTimerContext);
+    // Finalize state to ensure metrics and other state changes are committed.
+    this.stateAccessor.finalizeState();
   }
 
   private <K> void processOnWindowExpiration(Timer<K> timer) {
@@ -1545,6 +1547,8 @@ private <K> void processOnWindowExpiration(Timer<K> timer) {
         currentWindow = windowIterator.next();
         doFnInvoker.invokeOnWindowExpiration(onWindowExpirationContext);
       }
+      // Finalize state to ensure metrics and other state changes are committed.
+      this.stateAccessor.finalizeState();
     } finally {
       currentKey = null;
       currentTimer = null;