diff --git a/common/changes/@rushstack/heft-sass-plugin/fix-css-js_2025-08-31-00-57.json b/common/changes/@rushstack/heft-sass-plugin/fix-css-js_2025-08-31-00-57.json
new file mode 100644
index 00000000000..04717a659c4
--- /dev/null
+++ b/common/changes/@rushstack/heft-sass-plugin/fix-css-js_2025-08-31-00-57.json
@@ -0,0 +1,10 @@
+{
+  "changes": [
+    {
+      "packageName": "@rushstack/heft-sass-plugin",
+      "comment": "Fix an issue where generated `.scss.js` files can contain an incorrect path to the `.css` file.",
+      "type": "patch"
+    }
+  ],
+  "packageName": "@rushstack/heft-sass-plugin"
+}
\ No newline at end of file
diff --git a/heft-plugins/heft-sass-plugin/src/SassProcessor.ts b/heft-plugins/heft-sass-plugin/src/SassProcessor.ts
index baa38977a76..d3a7da77acc 100644
--- a/heft-plugins/heft-sass-plugin/src/SassProcessor.ts
+++ b/heft-plugins/heft-sass-plugin/src/SassProcessor.ts
@@ -781,7 +781,7 @@ export class SassProcessor {
 
     const filename: string = path.basename(relativeFilePath);
     const extensionStart: number = filename.lastIndexOf('.');
-    const cssPathFromJs: string = `./${relativeFilePath.slice(0, extensionStart)}.css`;
+    const cssPathFromJs: string = `./${filename.slice(0, extensionStart)}.css`;
     const relativeCssPath: string = `${relativeFilePath.slice(0, relativeFilePath.lastIndexOf('.'))}.css`;
 
     if (cssOutputFolders && cssOutputFolders.length > 0) {