diff --git a/packages/docusaurus-theme-classic/package.json b/packages/docusaurus-theme-classic/package.json
index 63fcff4e0a3d..09fa053d21a4 100644
--- a/packages/docusaurus-theme-classic/package.json
+++ b/packages/docusaurus-theme-classic/package.json
@@ -35,6 +35,7 @@
     "@docusaurus/utils-validation": "3.9.2",
     "@mdx-js/react": "^3.0.0",
     "clsx": "^2.0.0",
+    "copy-text-to-clipboard": "^3.2.0",
     "infima": "0.2.0-alpha.45",
     "lodash": "^4.17.21",
     "nprogress": "^0.2.0",
diff --git a/packages/docusaurus-theme-classic/src/theme/CodeBlock/Buttons/CopyButton/index.tsx b/packages/docusaurus-theme-classic/src/theme/CodeBlock/Buttons/CopyButton/index.tsx
index a09400029890..849b9fa32017 100644
--- a/packages/docusaurus-theme-classic/src/theme/CodeBlock/Buttons/CopyButton/index.tsx
+++ b/packages/docusaurus-theme-classic/src/theme/CodeBlock/Buttons/CopyButton/index.tsx
@@ -44,6 +44,19 @@ function ariaLabel(isCopied: boolean) {
       });
 }
 
+async function copyToClipboard(text: string) {
+  // The clipboard API is only defined in secure contexts (HTTPS / localhost).
+  // See https://developer.mozilla.org/en-US/docs/Web/API/Clipboard
+  if (navigator.clipboard) {
+    return navigator.clipboard.writeText(text);
+  }
+  // Fall back to copy-text-to-clipboard for non-secure contexts (e.g. HTTP
+  // on a local network). The fallback is lazily loaded to avoid bundle
+  // overhead for the common HTTPS case.
+  const {default: copy} = await import('copy-text-to-clipboard');
+  return copy(text);
+}
+
 function useCopyButton() {
   const {
     metadata: {code},
@@ -52,12 +65,14 @@ function useCopyButton() {
   const copyTimeout = useRef<number | undefined>(undefined);
 
   const copyCode = useCallback(() => {
-    navigator.clipboard.writeText(code).then(() => {
+    copyToClipboard(code).then(() => {
       setIsCopied(true);
       copyTimeout.current = window.setTimeout(() => {
         setIsCopied(false);
       }, 1000);
     });
+    // Errors are intentionally not caught so they remain unhandled and can
+    // be captured by observability tools (e.g. Sentry, PostHog).
   }, [code]);
 
   useEffect(() => () => window.clearTimeout(copyTimeout.current), []);
diff --git a/yarn.lock b/yarn.lock
index 7f9b9a8df2e8..07c274a231b6 100644
--- a/yarn.lock
+++ b/yarn.lock
@@ -6907,6 +6907,11 @@ cookie@~0.4.1:
   resolved "https://registry.yarnpkg.com/cookie/-/cookie-0.4.2.tgz#0e41f24de5ecf317947c82fc789e06a884824432"
   integrity sha512-aSWTXFzaKWkvHO1Ny/s+ePFpvKsPnjc551iI41v3ny/ow6tBG5Vd+FuqGNhh1LxOmVzOlGUriIlOaokOvhaStA==
 
+copy-text-to-clipboard@^3.2.0:
+  version "3.2.2"
+  resolved "https://registry.yarnpkg.com/copy-text-to-clipboard/-/copy-text-to-clipboard-3.2.2.tgz#99bc79db3f2d355ec33a08d573aff6804491ddb9"
+  integrity sha512-T6SqyLd1iLuqPA90J5N4cTalrtovCySh58iiZDGJ6FGznbclKh4UI+FGacQSgFzwKG77W7XT5gwbVEbd9cIH1A==
+
 copy-webpack-plugin@^11.0.0:
   version "11.0.0"
   resolved "https://registry.yarnpkg.com/copy-webpack-plugin/-/copy-webpack-plugin-11.0.0.tgz#96d4dbdb5f73d02dd72d0528d1958721ab72e04a"