diff --git a/change/@fluentui-react-storybook-addon-export-to-sandbox-4a111ae2-83ac-4fad-8039-eeed61b69743.json b/change/@fluentui-react-storybook-addon-export-to-sandbox-4a111ae2-83ac-4fad-8039-eeed61b69743.json
new file mode 100644
index 00000000000000..9cc726ff2a53d6
--- /dev/null
+++ b/change/@fluentui-react-storybook-addon-export-to-sandbox-4a111ae2-83ac-4fad-8039-eeed61b69743.json
@@ -0,0 +1,7 @@
+{
+  "type": "patch",
+  "comment": "fix: match backslash-separated preset paths so the addon finds its registration on Windows",
+  "packageName": "@fluentui/react-storybook-addon-export-to-sandbox",
+  "email": "array.knight@gmail.com",
+  "dependentChangeType": "patch"
+}
diff --git a/packages/react-components/react-storybook-addon-export-to-sandbox/src/webpack.ts b/packages/react-components/react-storybook-addon-export-to-sandbox/src/webpack.ts
index 8ebe39c87ae43c..4b51379589f001 100644
--- a/packages/react-components/react-storybook-addon-export-to-sandbox/src/webpack.ts
+++ b/packages/react-components/react-storybook-addon-export-to-sandbox/src/webpack.ts
@@ -16,7 +16,11 @@ export function webpack(config: WebpackFinalConfig, options: WebpackFinalOptions
 }
 
 const identity = <T extends unknown>(value: T) => value;
-const addonFilePattern = /react-storybook-addon-export-to-sandbox\/[a-z/]+.[jt]s$/;
+// Both path separators on purpose: on Windows the registered preset name is an absolute
+// path with backslashes (e.g. `...\react-storybook-addon-export-to-sandbox\temp\preset.ts`);
+// a forward-slash-only pattern fails to find the registration, silently drops the addon
+// options, and the full-source babel plugin then crashes on undefined `importMappings`.
+const addonFilePattern = /react-storybook-addon-export-to-sandbox[\\/][a-z\\/]+.[jt]s$/;
 const defaultOptions = {
   webpackRule: {},
   babelLoaderOptionsUpdater: identity,