diff --git a/packages/store/src/internal/unhandled-rxjs-error-callback.ts b/packages/store/src/internal/unhandled-rxjs-error-callback.ts
index dc5bd189e..c671312ff 100644
--- a/packages/store/src/internal/unhandled-rxjs-error-callback.ts
+++ b/packages/store/src/internal/unhandled-rxjs-error-callback.ts
@@ -2,17 +2,19 @@ import { config } from 'rxjs';
 
 const ɵɵunhandledRxjsErrorCallbacks = new WeakMap<any, VoidFunction>();
 
-const existingHandler = config.onUnhandledError;
-config.onUnhandledError = function (error: any) {
-  const unhandledErrorCallback = ɵɵunhandledRxjsErrorCallbacks.get(error);
-  if (unhandledErrorCallback) {
-    unhandledErrorCallback();
-  } else if (existingHandler) {
-    existingHandler.call(this, error);
-  } else {
-    throw error;
-  }
-};
+export function setupOnUnhandhedErrorHandler(): void {
+  const existingHandler = config.onUnhandledError;
+  config.onUnhandledError = function (error: any) {
+    const unhandledErrorCallback = ɵɵunhandledRxjsErrorCallbacks.get(error);
+    if (unhandledErrorCallback) {
+      unhandledErrorCallback();
+    } else if (existingHandler) {
+      existingHandler.call(this, error);
+    } else {
+      throw error;
+    }
+  };
+}
 
 export function executeUnhandledCallback(error: any) {
   const unhandledErrorCallback = ɵɵunhandledRxjsErrorCallbacks.get(error);
diff --git a/packages/store/src/standalone-features/initializers.ts b/packages/store/src/standalone-features/initializers.ts
index 406676e8c..282e45bf9 100644
--- a/packages/store/src/standalone-features/initializers.ts
+++ b/packages/store/src/standalone-features/initializers.ts
@@ -10,6 +10,7 @@ import { StatesAndDefaults } from '../internal/internals';
 import { SelectFactory } from '../decorators/select/select-factory';
 import { InternalStateOperations } from '../internal/state-operations';
 import { LifecycleStateManager } from '../internal/lifecycle-state-manager';
+import { setupOnUnhandhedErrorHandler } from '../internal/unhandled-rxjs-error-callback';
 
 /**
  * This function is shared by both NgModule and standalone features.
@@ -17,6 +18,12 @@ import { LifecycleStateManager } from '../internal/lifecycle-state-manager';
  * same initialization functionality.
  */
 export function rootStoreInitializer(): void {
+  // Override the RxJS `config.onUnhandledError` within the root store initializer,
+  // but only after other code has already executed.
+  // If users have a custom `config.onUnhandledError`, we might overwrite it too
+  // early and capture the original `config.onUnhandledError` before it is properly set.
+  setupOnUnhandhedErrorHandler();
+
   const prebootFns = inject(NGXS_PREBOOT_FNS, { optional: true }) || [];
   prebootFns.forEach(prebootFn => prebootFn());