diff --git a/scripts/build.js b/scripts/build.js
index 0dc11ce06b..873706f2ed 100644
--- a/scripts/build.js
+++ b/scripts/build.js
@@ -304,6 +304,25 @@ const lazyGrammarPlugin = {
 	},
 };
 
+/**
+ * Makes `require("prismjs")` return the default export directly with named
+ * exports as properties, so CJS consumers don't need `.default`.
+ *
+ * @type {Plugin}
+ */
+const cjsExportPlugin = {
+	name: 'cjs-default-export',
+	renderChunk (code) {
+		if (!code.includes('exports.default=')) {
+			return null;
+		}
+
+		code += 'module.exports=Object.assign(exports.default,exports);';
+
+		return { code, map: null };
+	},
+};
+
 /**
  * @param {MagicString} s
  * @returns {{ code: string; map: SourceMapInput }}
@@ -411,16 +430,20 @@ async function buildJS () {
 	const bundles = {
 		esm: {
 			rollupOptions: defaultRollupOptions,
-			outputOptions: defaultOutputOptions,
+			outputOptions: {
+				...defaultOutputOptions,
+				format: 'es',
+			},
 		},
 		cjs: {
 			rollupOptions: {
 				...defaultRollupOptions,
-				plugins: [...defaultRollupOptions.plugins, commonjs()],
+				plugins: [...defaultRollupOptions.plugins, commonjs(), cjsExportPlugin],
 			},
 			outputOptions: {
 				...defaultOutputOptions,
 				dir: './dist/cjs',
+				format: 'cjs',
 			},
 		},
 	};
@@ -430,6 +453,14 @@ async function buildJS () {
 			bundle.build = await rollup(bundle.rollupOptions);
 			await bundle.build.write(bundle.outputOptions);
 		}
+		// The root package.json has "type": "module", so Node treats all .js files as ESM.
+		// This overrides that for the CJS directory, since Node uses the nearest parent
+		// package.json to determine the module system: https://nodejs.org/api/packages.html#type
+		await writeFile(
+			path.join(DIST_DIR, 'cjs', 'package.json'),
+			JSON.stringify({ type: 'commonjs' }),
+			'utf-8'
+		);
 	}
 	finally {
 		for (const bundle of Object.values(bundles)) {