diff --git a/.gitignore b/.gitignore
index 9f07f6ce6dd..842e6a5b45b 100644
--- a/.gitignore
+++ b/.gitignore
@@ -55,6 +55,7 @@ unused-exports*.txt
 
 # wdio test output
 test/wdio/test-components
+test/wdio/test-components-no-external-runtime
 test/wdio/www-global-script/
 test/wdio/www-prerender-script
 test/wdio/www-invisible-prehydration/
diff --git a/src/runtime/proxy-component.ts b/src/runtime/proxy-component.ts
index 2b2fda3b93a..8f7d26a097c 100644
--- a/src/runtime/proxy-component.ts
+++ b/src/runtime/proxy-component.ts
@@ -29,24 +29,25 @@ export const proxyComponent = (
    * @ref https://web.dev/articles/more-capable-form-controls#lifecycle_callbacks
    */
   if (BUILD.formAssociated && cmpMeta.$flags$ & CMP_FLAGS.formAssociated && flags & PROXY_FLAGS.isElementConstructor) {
-    FORM_ASSOCIATED_CUSTOM_ELEMENT_CALLBACKS.forEach((cbName) =>
+    FORM_ASSOCIATED_CUSTOM_ELEMENT_CALLBACKS.forEach((cbName) => {
+      const originalFormAssociatedCallback = prototype[cbName];
       Object.defineProperty(prototype, cbName, {
         value(this: d.HostElement, ...args: any[]) {
           const hostRef = getHostRef(this);
-          const elm = BUILD.lazyLoad ? hostRef.$hostElement$ : this;
-          const instance: d.ComponentInterface = BUILD.lazyLoad ? hostRef.$lazyInstance$ : elm;
+          const instance: d.ComponentInterface = BUILD.lazyLoad ? hostRef.$lazyInstance$ : this;
           if (!instance) {
-            hostRef.$onReadyPromise$.then((instance: d.ComponentInterface) => {
-              const cb = instance[cbName];
-              typeof cb === 'function' && cb.call(instance, ...args);
+            hostRef.$onReadyPromise$.then((asyncInstance: d.ComponentInterface) => {
+              const cb = asyncInstance[cbName];
+              typeof cb === 'function' && cb.call(asyncInstance, ...args);
             });
           } else {
-            const cb = instance[cbName];
+            // Use the method on `instance` if `lazyLoad` is set, otherwise call the original method to avoid an infinite loop.
+            const cb = BUILD.lazyLoad ? instance[cbName] : originalFormAssociatedCallback;
             typeof cb === 'function' && cb.call(instance, ...args);
           }
         },
-      }),
-    );
+      });
+    });
   }
 
   if ((BUILD.member && cmpMeta.$members$) || (BUILD.watchCallback && (cmpMeta.$watchers$ || Cstr.watchers))) {
diff --git a/test/wdio/no-external-runtime.stencil.config.ts b/test/wdio/no-external-runtime.stencil.config.ts
new file mode 100644
index 00000000000..bb3d18bef56
--- /dev/null
+++ b/test/wdio/no-external-runtime.stencil.config.ts
@@ -0,0 +1,15 @@
+import type { Config } from '../../internal/index.js';
+
+export const config: Config = {
+  namespace: 'TestNoExternalRuntimeApp',
+  tsconfig: 'tsconfig-no-external-runtime.json',
+  outputTargets: [
+    {
+      type: 'dist-custom-elements',
+      dir: 'test-components-no-external-runtime',
+      externalRuntime: false,
+      includeGlobalScripts: false,
+    },
+  ],
+  srcDir: 'no-external-runtime',
+};
diff --git a/test/wdio/no-external-runtime/components.d.ts b/test/wdio/no-external-runtime/components.d.ts
new file mode 100644
index 00000000000..ce611509d45
--- /dev/null
+++ b/test/wdio/no-external-runtime/components.d.ts
@@ -0,0 +1,37 @@
+/* eslint-disable */
+/* tslint:disable */
+/**
+ * This is an autogenerated file created by the Stencil compiler.
+ * It contains typing information for all components that exist in this project.
+ */
+import { HTMLStencilElement, JSXBase } from "@stencil/core/internal";
+export namespace Components {
+    interface CustomElementsFormAssociated {
+    }
+}
+declare global {
+    interface HTMLCustomElementsFormAssociatedElement extends Components.CustomElementsFormAssociated, HTMLStencilElement {
+    }
+    var HTMLCustomElementsFormAssociatedElement: {
+        prototype: HTMLCustomElementsFormAssociatedElement;
+        new (): HTMLCustomElementsFormAssociatedElement;
+    };
+    interface HTMLElementTagNameMap {
+        "custom-elements-form-associated": HTMLCustomElementsFormAssociatedElement;
+    }
+}
+declare namespace LocalJSX {
+    interface CustomElementsFormAssociated {
+    }
+    interface IntrinsicElements {
+        "custom-elements-form-associated": CustomElementsFormAssociated;
+    }
+}
+export { LocalJSX as JSX };
+declare module "@stencil/core" {
+    export namespace JSX {
+        interface IntrinsicElements {
+            "custom-elements-form-associated": LocalJSX.CustomElementsFormAssociated & JSXBase.HTMLAttributes<HTMLCustomElementsFormAssociatedElement>;
+        }
+    }
+}
diff --git a/test/wdio/no-external-runtime/custom-elements-form-associated/cmp.test.tsx b/test/wdio/no-external-runtime/custom-elements-form-associated/cmp.test.tsx
new file mode 100644
index 00000000000..2627985fbd8
--- /dev/null
+++ b/test/wdio/no-external-runtime/custom-elements-form-associated/cmp.test.tsx
@@ -0,0 +1,67 @@
+import { h } from '@stencil/core';
+import { render } from '@wdio/browser-runner/stencil';
+
+import { defineCustomElement } from '../../test-components-no-external-runtime/custom-elements-form-associated.js';
+
+describe('custome elements form associated', function () {
+  beforeEach(() => {
+    defineCustomElement();
+    render({
+      template: () => (
+        <form>
+          <custom-elements-form-associated name="test-input"></custom-elements-form-associated>
+          <input type="reset" value="Reset" />
+        </form>
+      ),
+    });
+  });
+
+  it('should render without errors', async () => {
+    const elm = $('custom-elements-form-associated');
+    await expect(elm).toBePresent();
+  });
+
+  describe('form associated custom element lifecycle callback', () => {
+    it('should trigger "formAssociated"', async () => {
+      const formEl = $('form');
+      await expect(formEl).toHaveProperty('ariaLabel', 'asdfasdf');
+    });
+
+    it('should trigger "formResetCallback"', async () => {
+      const resetBtn = $('input[type="reset"]');
+      await resetBtn.click();
+
+      await resetBtn.waitForStable();
+
+      const formEl = $('form');
+      await expect(formEl).toHaveProperty('ariaLabel', 'formResetCallback called');
+    });
+
+    it('should trigger "formDisabledCallback"', async () => {
+      const elm = document.body.querySelector('custom-elements-form-associated');
+      const formEl = $('form');
+
+      elm.setAttribute('disabled', 'disabled');
+
+      await formEl.waitForStable();
+      await expect(formEl).toHaveProperty('ariaLabel', 'formDisabledCallback called with true');
+
+      elm.removeAttribute('disabled');
+      await formEl.waitForStable();
+      await expect(formEl).toHaveProperty('ariaLabel', 'formDisabledCallback called with false');
+    });
+  });
+
+  it('should link up to the surrounding form', async () => {
+    // this shows that the element has, through the `ElementInternals`
+    // interface, been able to set a value in the surrounding form
+    await browser.waitUntil(
+      async () => {
+        const formEl = document.body.querySelector('form');
+        expect(new FormData(formEl).get('test-input')).toBe('my default value');
+        return true;
+      },
+      { timeoutMsg: 'form associated value never changed' },
+    );
+  });
+});
diff --git a/test/wdio/no-external-runtime/custom-elements-form-associated/cmp.tsx b/test/wdio/no-external-runtime/custom-elements-form-associated/cmp.tsx
new file mode 100644
index 00000000000..bfce0129014
--- /dev/null
+++ b/test/wdio/no-external-runtime/custom-elements-form-associated/cmp.tsx
@@ -0,0 +1,25 @@
+import { AttachInternals, Component, h } from '@stencil/core';
+
+@Component({
+  tag: 'custom-elements-form-associated',
+  formAssociated: true,
+  shadow: true,
+})
+export class CustomElementsFormAssociated {
+  @AttachInternals() internals: ElementInternals;
+
+  componentWillLoad() {
+    this.internals.setFormValue('my default value');
+  }
+
+  formAssociatedCallback(form: HTMLCustomElementsFormAssociatedElement) {
+    form.ariaLabel = 'formAssociated called';
+    // this is a regression test for #5106 which ensures that `this` is
+    // resolved correctly
+    this.internals.setValidity({});
+  }
+
+  render() {
+    return <input type="text" />;
+  }
+}
diff --git a/test/wdio/package.json b/test/wdio/package.json
index 60db734854f..0ab4bc68c5d 100644
--- a/test/wdio/package.json
+++ b/test/wdio/package.json
@@ -3,12 +3,13 @@
   "type": "module",
   "version": "0.0.0",
   "scripts": {
-    "build": "run-s build.test-sibling build.main build.global-script build.prerender build.invisible-prehydration",
+    "build": "run-s build.no-external-runtime build.test-sibling build.main build.global-script build.prerender build.invisible-prehydration",
     "build.main": "node ../../bin/stencil build --debug --es5",
     "build.global-script": "node ../../bin/stencil build --debug --es5 --config global-script.stencil.config.ts",
     "build.test-sibling": "cd test-sibling && npm run build",
     "build.prerender": "node ../../bin/stencil build --config prerender.stencil.config.ts --prerender --debug && node ./test-prerender/prerender.js && node ./test-prerender/no-script-build.js",
     "build.invisible-prehydration": "node ../../bin/stencil build --debug --es5 --config invisible-prehydration.stencil.config.ts",
+    "build.no-external-runtime": "node ../../bin/stencil build --debug --es5 --config no-external-runtime.stencil.config.ts",
     "test": "run-s build wdio",
     "wdio": "wdio run ./wdio.conf.ts"
   },
diff --git a/test/wdio/setup.ts b/test/wdio/setup.ts
index fe4500d79b8..9309cb14e4c 100644
--- a/test/wdio/setup.ts
+++ b/test/wdio/setup.ts
@@ -13,6 +13,7 @@ const testRequiresManualSetup =
   window.__wdioSpec__.includes('custom-elements-output-tag-class-different') ||
   window.__wdioSpec__.includes('custom-elements-delegates-focus') ||
   window.__wdioSpec__.includes('custom-elements-output') ||
+  window.__wdioSpec__.includes('no-external-runtime') ||
   window.__wdioSpec__.includes('global-script') ||
   window.__wdioSpec__.endsWith('custom-tag-name.test.tsx') ||
   window.__wdioSpec__.endsWith('page-list.test.ts');
diff --git a/test/wdio/tsconfig-no-external-runtime.json b/test/wdio/tsconfig-no-external-runtime.json
new file mode 100644
index 00000000000..532f86cd342
--- /dev/null
+++ b/test/wdio/tsconfig-no-external-runtime.json
@@ -0,0 +1,5 @@
+{
+  "extends": "./tsconfig-stencil.json",
+  "include": ["no-external-runtime"],
+  "exclude": ["no-external-runtime/**/*.test.tsx"]
+}
diff --git a/test/wdio/tsconfig-stencil.json b/test/wdio/tsconfig-stencil.json
index ebaaf789f82..dfbca06b847 100644
--- a/test/wdio/tsconfig-stencil.json
+++ b/test/wdio/tsconfig-stencil.json
@@ -38,6 +38,9 @@
     "./test-sibling/**/*.tsx",
     // we also exclude the files in the invisible-prehydration directory
     "./invisible-prehydration/**/*.tsx",
-    "./invisible-prehydration/**/*.ts"
+    "./invisible-prehydration/**/*.ts",
+    // exclude no-external-runtime because they are built separately with `externalRuntime: false`
+    "./no-external-runtime/**/*.tsx",
+    "./no-external-runtime/**/*.ts",
   ]
 }