diff --git a/packages/plugin-vite/src/plugins/patches/commonjs.ts b/packages/plugin-vite/src/plugins/patches/commonjs.ts
index 40f1991227e..8d967f9d6a2 100644
--- a/packages/plugin-vite/src/plugins/patches/commonjs.ts
+++ b/packages/plugin-vite/src/plugins/patches/commonjs.ts
@@ -189,19 +189,14 @@ export function cjsPlugin(
             );
           }
 
-          const exportNamed = new Map<string, string>();
-
           const idExports: types.ExportSpecifier[] = [];
           for (const name of exported) {
             if (name === "default") {
-              exportNamed.set(name, name);
               continue;
             }
 
             const id = path.scope.generateUidIdentifier(name);
 
-            exportNamed.set(id.name, name);
-
             path.pushContainer(
               "body",
               t.variableDeclaration(
@@ -227,40 +222,61 @@ export function cjsPlugin(
             );
           }
 
-          if (exportNamed.size > 0 || exportedNs.size > 0 || hasEsModule) {
+          if (exported.size > 0 || exportedNs.size > 0 || hasEsModule) {
             const id = path.scope.generateUidIdentifier("__default");
 
             path.pushContainer(
               "body",
-              t.variableDeclaration("const", [
+              t.variableDeclaration("let", [
                 t.variableDeclarator(
                   id,
+                ),
+              ]),
+            );
+
+            path.pushContainer(
+              "body",
+              t.ifStatement(
+                t.logicalExpression(
+                  "&&",
                   t.logicalExpression(
-                    "??",
-                    t.memberExpression(
+                    "&&",
+                    t.binaryExpression(
+                      "===",
+                      t.unaryExpression("typeof", t.identifier("exports")),
+                      t.stringLiteral("object"),
+                    ),
+                    t.binaryExpression(
+                      "!==",
                       t.identifier("exports"),
-                      t.identifier("default"),
+                      t.nullLiteral(),
                     ),
+                  ),
+                  t.binaryExpression(
+                    "in",
+                    t.stringLiteral("default"),
                     t.identifier("exports"),
                   ),
                 ),
-              ]),
-            );
-
-            for (const [local, exported] of exportNamed.entries()) {
-              if (exported === "default") continue;
-
-              path.pushContainer(
-                "body",
-                t.expressionStatement(
-                  t.assignmentExpression(
-                    "=",
-                    t.memberExpression(id, t.identifier(exported)),
-                    t.identifier(local),
+                t.blockStatement([
+                  t.expressionStatement(
+                    t.assignmentExpression(
+                      "=",
+                      id,
+                      t.memberExpression(
+                        t.identifier("exports"),
+                        t.identifier("default"),
+                      ),
+                    ),
                   ),
-                ),
-              );
-            }
+                ]),
+                t.blockStatement([
+                  t.expressionStatement(
+                    t.assignmentExpression("=", id, t.identifier("exports")),
+                  ),
+                ]),
+              ),
+            );
 
             for (let i = 0; i < mappedNs.length; i++) {
               const mapped = mappedNs[i];
@@ -268,53 +284,79 @@ export function cjsPlugin(
               const key = path.scope.generateUid("k");
               path.pushContainer(
                 "body",
-                t.forInStatement(
-                  t.variableDeclaration("var", [
-                    t.variableDeclarator(t.identifier(key)),
-                  ]),
-                  t.identifier(mapped),
-                  t.ifStatement(
+                t.ifStatement(
+                  t.logicalExpression(
+                    "&&",
                     t.logicalExpression(
                       "&&",
+                      t.binaryExpression(
+                        "===",
+                        t.unaryExpression("typeof", t.identifier("exports")),
+                        t.stringLiteral("object"),
+                      ),
+                      t.binaryExpression(
+                        "!==",
+                        t.identifier("exports"),
+                        t.nullLiteral(),
+                      ),
+                    ),
+                    t.unaryExpression(
+                      "!",
+                      t.binaryExpression(
+                        "in",
+                        t.stringLiteral("default"),
+                        t.identifier("exports"),
+                      ),
+                    ),
+                  ),
+                  t.forInStatement(
+                    t.variableDeclaration("var", [
+                      t.variableDeclarator(t.identifier(key)),
+                    ]),
+                    t.identifier(mapped),
+                    t.ifStatement(
                       t.logicalExpression(
                         "&&",
-                        t.binaryExpression(
-                          "!==",
-                          t.identifier(key),
-                          t.stringLiteral("default"),
-                        ),
-                        t.binaryExpression(
-                          "!==",
-                          t.identifier(key),
-                          t.stringLiteral("__esModule"),
+                        t.logicalExpression(
+                          "&&",
+                          t.binaryExpression(
+                            "!==",
+                            t.identifier(key),
+                            t.stringLiteral("default"),
+                          ),
+                          t.binaryExpression(
+                            "!==",
+                            t.identifier(key),
+                            t.stringLiteral("__esModule"),
+                          ),
                         ),
-                      ),
-                      t.callExpression(
-                        t.memberExpression(
+                        t.callExpression(
                           t.memberExpression(
                             t.memberExpression(
-                              t.identifier("Object"),
-                              t.identifier("prototype"),
+                              t.memberExpression(
+                                t.identifier("Object"),
+                                t.identifier("prototype"),
+                              ),
+                              t.identifier("hasOwnProperty"),
                             ),
-                            t.identifier("hasOwnProperty"),
+                            t.identifier("call"),
                           ),
-                          t.identifier("call"),
+                          [t.identifier(mapped), t.identifier(key)],
                         ),
-                        [t.identifier(mapped), t.identifier(key)],
                       ),
-                    ),
-                    t.expressionStatement(
-                      t.assignmentExpression(
-                        "=",
-                        t.memberExpression(
-                          t.cloneNode(id, true),
-                          t.identifier(key),
-                          true,
-                        ),
-                        t.memberExpression(
-                          t.identifier(mapped),
-                          t.identifier(key),
-                          true,
+                      t.expressionStatement(
+                        t.assignmentExpression(
+                          "=",
+                          t.memberExpression(
+                            t.cloneNode(id, true),
+                            t.identifier(key),
+                            true,
+                          ),
+                          t.memberExpression(
+                            t.identifier(mapped),
+                            t.identifier(key),
+                            true,
+                          ),
                         ),
                       ),
                     ),
@@ -663,6 +705,7 @@ export function cjsPlugin(
               state.set(HAS_ES_MODULE, true);
             } else if (left.isMemberExpression()) {
               if (isModuleExports(t, left.node)) {
+                // Should always try to create synthetic default export in this case.
                 exported.add("default");
 
                 if (t.isObjectExpression(expr.node.right)) {
diff --git a/packages/plugin-vite/src/plugins/patches/commonjs_test.ts b/packages/plugin-vite/src/plugins/patches/commonjs_test.ts
index 1f4e55444b9..99695c56c2a 100644
--- a/packages/plugin-vite/src/plugins/patches/commonjs_test.ts
+++ b/packages/plugin-vite/src/plugins/patches/commonjs_test.ts
@@ -26,7 +26,13 @@ Object.defineProperty(module, "exports", {
   }
 });`;
 
-const DEFAULT_EXPORT = `const _default = exports.default ?? exports;`;
+const DEFAULT_EXPORT = `let _default;
+if (typeof exports === "object" && exports !== null && "default" in exports) {
+  _default = exports.default;
+} else {
+  _default = exports;
+}`;
+
 const DEFAULT_EXPORT_END = `export default _default;
 export var __require = exports;`;
 const IMPORT_REQUIRE = `import { createRequire } from "node:module";
@@ -65,7 +71,6 @@ exports.foo = 'foo';
 var _foo = exports.foo;
 export { _foo as foo };
 ${DEFAULT_EXPORT}
-_default.foo = _foo;
 ${DEFAULT_EXPORT_END}
 ${EXPORT_ES_MODULE}`,
   });
@@ -83,7 +88,6 @@ module.exports.foo = 'foo';
 var _foo = exports.foo;
 export { _foo as foo };
 ${DEFAULT_EXPORT}
-_default.foo = _foo;
 ${DEFAULT_EXPORT_END}
 ${EXPORT_ES_MODULE}`,
   });
@@ -104,7 +108,6 @@ const foo = 'also bar';
 var _foo = exports.foo;
 export { _foo as foo };
 ${DEFAULT_EXPORT}
-_default.foo = _foo;
 ${DEFAULT_EXPORT_END}
 ${EXPORT_ES_MODULE}`,
   });
@@ -125,7 +128,6 @@ exports.foo = 'bar';
 var _foo = exports.foo;
 export { _foo as foo };
 ${DEFAULT_EXPORT}
-_default.foo = _foo;
 ${DEFAULT_EXPORT_END}
 ${EXPORT_ES_MODULE}`,
   });
@@ -137,9 +139,8 @@ Deno.test("commonjs - esModule flag only", () => {
     expected: `Object.defineProperty(exports, "__esModule", {
   value: true
 });
-const _default = exports.default ?? exports;
-export default _default;
-export var __require = exports;
+${DEFAULT_EXPORT}
+${DEFAULT_EXPORT_END}
 ${EXPORT_ES_MODULE}`,
   });
 });
@@ -151,9 +152,8 @@ Deno.test("commonjs - esModule flag only #2", () => {
     expected: `Object.defineProperty(module.exports, "__esModule", {
   value: true
 });
-const _default = exports.default ?? exports;
-export default _default;
-export var __require = exports;
+${DEFAULT_EXPORT}
+${DEFAULT_EXPORT_END}
 ${EXPORT_ES_MODULE}`,
   });
 });
@@ -164,9 +164,8 @@ Deno.test("commonjs - esModule flag only minified #3", () => {
     expected: `Object.defineProperty(exports, '__esModule', {
   value: !0
 });
-const _default = exports.default ?? exports;
-export default _default;
-export var __require = exports;
+${DEFAULT_EXPORT}
+${DEFAULT_EXPORT_END}
 ${EXPORT_ES_MODULE}`,
   });
 });
@@ -187,8 +186,6 @@ var _foo = exports.foo;
 var _bar = exports.bar;
 export { _foo as foo, _bar as bar };
 ${DEFAULT_EXPORT}
-_default.foo = _foo;
-_default.bar = _bar;
 ${DEFAULT_EXPORT_END}
 ${EXPORT_ES_MODULE}`,
   });
@@ -271,7 +268,6 @@ exports.trace = 'foo';
 var _trace = exports.trace;
 export { _trace as trace };
 ${DEFAULT_EXPORT}
-_default.trace = _trace;
 ${DEFAULT_EXPORT_END}
 ${EXPORT_ES_MODULE}`,
   });
@@ -290,7 +286,6 @@ exports.foo = 'foo';
 var _foo = exports.foo;
 export { _foo as foo };
 ${DEFAULT_EXPORT}
-_default.foo = _foo;
 ${DEFAULT_EXPORT_END}
 ${EXPORT_ES_MODULE}`,
   });
@@ -307,7 +302,6 @@ exports.foo = utils_1.foo;
 var _foo = exports.foo;
 export { _foo as foo };
 ${DEFAULT_EXPORT}
-_default.foo = _foo;
 ${DEFAULT_EXPORT_END}`,
   });
 });
@@ -323,7 +317,6 @@ exports.foo = utils_1.foo;
 var _foo = exports.foo;
 export { _foo as foo };
 ${DEFAULT_EXPORT}
-_default.foo = _foo;
 ${DEFAULT_EXPORT_END}`,
   });
 });
@@ -342,7 +335,6 @@ exports._globalThis = typeof globalThis === 'object' ? globalThis : global;
 var _globalThis = exports._globalThis;
 export { _globalThis };
 ${DEFAULT_EXPORT}
-_default._globalThis = _globalThis;
 ${DEFAULT_EXPORT_END}
 ${EXPORT_ES_MODULE}`,
   });
@@ -362,7 +354,6 @@ exports.foo = foo;
 var _foo = exports.foo;
 export { _foo as foo };
 ${DEFAULT_EXPORT}
-_default.foo = _foo;
 ${DEFAULT_EXPORT_END}
 ${EXPORT_ES_MODULE}`,
   });
@@ -375,7 +366,7 @@ Deno.test("commonjs - detect esbuild shims", () => {
 import * as _ns from "./globalThis";
 export * from "./globalThis";
 ${DEFAULT_EXPORT}
-for (var _k in _ns) if (_k !== "default" && _k !== "__esModule" && Object.prototype.hasOwnProperty.call(_ns, _k)) _default[_k] = _ns[_k];
+if (typeof exports === "object" && exports !== null && !("default" in exports)) for (var _k in _ns) if (_k !== "default" && _k !== "__esModule" && Object.prototype.hasOwnProperty.call(_ns, _k)) _default[_k] = _ns[_k];
 ${DEFAULT_EXPORT_END}`,
   });
 });
@@ -400,7 +391,6 @@ exports.VERSION = '1.9.0';
 var _VERSION = exports.VERSION;
 export { _VERSION as VERSION };
 ${DEFAULT_EXPORT}
-_default.VERSION = _VERSION;
 ${DEFAULT_EXPORT_END}`,
   });
 });
@@ -425,7 +415,6 @@ var DiagLogLevel;
 var _DiagLogLevel = exports.DiagLogLevel;
 export { _DiagLogLevel as DiagLogLevel };
 ${DEFAULT_EXPORT}
-_default.DiagLogLevel = _DiagLogLevel;
 ${DEFAULT_EXPORT_END}
 ${EXPORT_ES_MODULE}`,
   });
@@ -461,7 +450,6 @@ module.exports = {
 var _foo = exports.foo;
 export { _foo as foo };
 ${DEFAULT_EXPORT}
-_default.foo = _foo;
 ${DEFAULT_EXPORT_END}
 ${EXPORT_ES_MODULE}`,
   });
@@ -479,7 +467,6 @@ Deno.test("commonjs - detect iife wrapper", () => {
 var _foo = exports.foo;
 export { _foo as foo };
 ${DEFAULT_EXPORT}
-_default.foo = _foo;
 ${DEFAULT_EXPORT_END}`,
   });
 });
@@ -521,7 +508,7 @@ Object.defineProperty(exports, "__esModule", {
 });
 export * from "./node";
 ${DEFAULT_EXPORT}
-for (var _k in _ns) if (_k !== "default" && _k !== "__esModule" && Object.prototype.hasOwnProperty.call(_ns, _k)) _default[_k] = _ns[_k];
+if (typeof exports === "object" && exports !== null && !("default" in exports)) for (var _k in _ns) if (_k !== "default" && _k !== "__esModule" && Object.prototype.hasOwnProperty.call(_ns, _k)) _default[_k] = _ns[_k];
 ${DEFAULT_EXPORT_END}
 ${EXPORT_ES_MODULE}`,
   });
@@ -537,7 +524,6 @@ module.exports = {
 var _foo = exports.foo;
 export { _foo as foo };
 ${DEFAULT_EXPORT}
-_default.foo = _foo;
 ${DEFAULT_EXPORT_END}`,
   });
 });
@@ -634,7 +620,6 @@ Deno.test("commonjs - wrapped iife binding", () => {
 var _foo = exports.foo;
 export { _foo as foo };
 ${DEFAULT_EXPORT}
-_default.foo = _foo;
 ${DEFAULT_EXPORT_END}`,
   });
 });
@@ -719,3 +704,22 @@ var __importDefault = this && this.__importDefault || function (mod) {
 const node_events_1 = __importDefault(_mod.default ?? _mod);`,
   });
 });
+
+Deno.test("commonjs imitating esm - default export exists", () => {
+  runTest({
+    input: `module.exports = {
+  'default': 'string',
+  otherExport: 1
+};
+`,
+    expected: `${INIT}
+module.exports = {
+  'default': 'string',
+  otherExport: 1
+};
+var _otherExport = exports.otherExport;
+export { _otherExport as otherExport };
+${DEFAULT_EXPORT}
+${DEFAULT_EXPORT_END}`,
+  });
+});