diff --git a/packages/react-native/ReactAndroid/api/ReactAndroid.api b/packages/react-native/ReactAndroid/api/ReactAndroid.api
index 018c2ef4826..f70386ad9e1 100644
--- a/packages/react-native/ReactAndroid/api/ReactAndroid.api
+++ b/packages/react-native/ReactAndroid/api/ReactAndroid.api
@@ -1746,9 +1746,9 @@ public abstract interface class com/facebook/react/common/ShakeDetector$ShakeLis
 	public abstract fun onShake ()V
 }
 
-public class com/facebook/react/common/SingleThreadAsserter {
+public final class com/facebook/react/common/SingleThreadAsserter {
 	public fun <init> ()V
-	public fun assertNow ()V
+	public final fun assertNow ()V
 }
 
 public final class com/facebook/react/common/StandardCharsets {
diff --git a/packages/react-native/ReactAndroid/src/main/java/com/facebook/react/common/SingleThreadAsserter.java b/packages/react-native/ReactAndroid/src/main/java/com/facebook/react/common/SingleThreadAsserter.java
deleted file mode 100644
index 0fa4a093ecd..00000000000
--- a/packages/react-native/ReactAndroid/src/main/java/com/facebook/react/common/SingleThreadAsserter.java
+++ /dev/null
@@ -1,26 +0,0 @@
-/*
- * Copyright (c) Meta Platforms, Inc. and affiliates.
- *
- * This source code is licensed under the MIT license found in the
- * LICENSE file in the root directory of this source tree.
- */
-
-package com.facebook.react.common;
-
-import androidx.annotation.Nullable;
-import com.facebook.infer.annotation.Assertions;
-import com.facebook.infer.annotation.Nullsafe;
-
-/** Simple class for asserting that operations only run on a single thread. */
-@Nullsafe(Nullsafe.Mode.LOCAL)
-public class SingleThreadAsserter {
-  private @Nullable Thread mThread = null;
-
-  public void assertNow() {
-    Thread current = Thread.currentThread();
-    if (mThread == null) {
-      mThread = current;
-    }
-    Assertions.assertCondition(mThread == current);
-  }
-}
diff --git a/packages/react-native/ReactAndroid/src/main/java/com/facebook/react/common/SingleThreadAsserter.kt b/packages/react-native/ReactAndroid/src/main/java/com/facebook/react/common/SingleThreadAsserter.kt
new file mode 100644
index 00000000000..dea4cebe617
--- /dev/null
+++ b/packages/react-native/ReactAndroid/src/main/java/com/facebook/react/common/SingleThreadAsserter.kt
@@ -0,0 +1,23 @@
+/*
+ * Copyright (c) Meta Platforms, Inc. and affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ */
+
+package com.facebook.react.common
+
+import com.facebook.infer.annotation.Assertions
+
+/** Simple class for asserting that operations only run on a single thread. */
+public class SingleThreadAsserter {
+  private var thread: Thread? = null
+
+  public fun assertNow() {
+    val currentThread = Thread.currentThread()
+    if (thread == null) {
+      thread = currentThread
+    }
+    Assertions.assertCondition(thread == currentThread)
+  }
+}