diff --git a/lib/library/SystemLibraryPlugin.js b/lib/library/SystemLibraryPlugin.js
index 380962091..36526fa53 100644
--- a/lib/library/SystemLibraryPlugin.js
+++ b/lib/library/SystemLibraryPlugin.js
@@ -133,7 +133,20 @@ class SystemLibraryPlugin extends AbstractLibraryPlugin {
 											chunk.runtime
 										);
 										if (used) {
-											if (otherUnused || used !== exportInfo.name) {
+											if (used === "default" && exportInfo.name === "default") {
+												instructions.push(
+													Template.asString([
+														"if (typeof module.default !== 'undefined') {",
+														Template.indent([
+															`${external}.default = module.default;`
+														]),
+														"} else {",
+														Template.indent([`${external} = module;`]),
+														"}"
+													])
+												);
+												handledNames.push(exportInfo.name);
+											} else if (otherUnused || used !== exportInfo.name) {
 												instructions.push(
 													`${external}${propertyAccess([
 														used
@@ -172,9 +185,24 @@ class SystemLibraryPlugin extends AbstractLibraryPlugin {
 										} else {
 											instructions.push(
 												Template.asString([
-													"Object.keys(module).forEach(function(key) {",
-													Template.indent([`${external}[key] = module[key];`]),
-													"});"
+													"if (typeof module.default !== 'undefined') {",
+													Template.indent([
+														"Object.keys(module).forEach(function(key) {",
+														Template.indent([
+															`${external}[key] = module[key];`
+														]),
+														"});"
+													]),
+													"} else {",
+													Template.indent([
+														`${external} = module;`,
+														"Object.keys(module).forEach(function(key) {",
+														Template.indent([
+															`${external}[key] = module[key];`
+														]),
+														"});"
+													]),
+													"}"
 												])
 											);
 										}
diff --git a/test/configCases/target/system-default-import-fix/index.js b/test/configCases/target/system-default-import-fix/index.js
new file mode 100644
index 000000000..83e9d9f92
--- /dev/null
+++ b/test/configCases/target/system-default-import-fix/index.js
@@ -0,0 +1,19 @@
+import React, { useEffect } from "react";
+
+/* This test verifies that default imports work correctly with SystemJS externals
+ * when the external module doesn't have a default property (e.g., React)
+ */
+
+it("should correctly handle default import from SystemJS external", function() {
+	// React should be the entire module object, not undefined
+	expect(React).toBeDefined();
+	expect(typeof React).toBe("object");
+	expect(React.Component).toBeDefined();
+	expect(React.Fragment).toBeDefined();
+	
+	// Named imports should still work
+	expect(typeof useEffect).toBe("function");
+	
+	// The default import should not be undefined
+	expect(React).not.toBeUndefined();
+});
diff --git a/test/configCases/target/system-default-import-fix/react-with-default.js b/test/configCases/target/system-default-import-fix/react-with-default.js
new file mode 100644
index 000000000..f8e36b12e
--- /dev/null
+++ b/test/configCases/target/system-default-import-fix/react-with-default.js
@@ -0,0 +1,26 @@
+// Mock React module that HAS a default property
+// This simulates ES6 modules with default exports
+const React = {
+	Component: function Component() {},
+	Fragment: Symbol("react.fragment"),
+	Profiler: Symbol("react.profiler"),
+	useEffect: function useEffect(callback, deps) {
+		return callback();
+	},
+	useState: function useState(initial) {
+		return [initial, function() {}];
+	},
+	createElement: function createElement(type, props, ...children) {
+		return { type, props, children };
+	}
+};
+
+// Export with default property (ES6 module format)
+module.exports = React;
+module.exports.default = React;
+module.exports.useEffect = React.useEffect;
+module.exports.Component = React.Component;
+module.exports.Fragment = React.Fragment;
+module.exports.Profiler = React.Profiler;
+module.exports.useState = React.useState;
+module.exports.createElement = React.createElement;
diff --git a/test/configCases/target/system-default-import-fix/react.js b/test/configCases/target/system-default-import-fix/react.js
new file mode 100644
index 000000000..2b59fb098
--- /dev/null
+++ b/test/configCases/target/system-default-import-fix/react.js
@@ -0,0 +1,25 @@
+// Mock React module that doesn't have a default property
+// This simulates how React is typically exported in SystemJS environments
+const React = {
+	Component: function Component() {},
+	Fragment: Symbol("react.fragment"),
+	Profiler: Symbol("react.profiler"),
+	useEffect: function useEffect(callback, deps) {
+		return callback();
+	},
+	useState: function useState(initial) {
+		return [initial, function() {}];
+	},
+	createElement: function createElement(type, props, ...children) {
+		return { type, props, children };
+	}
+};
+
+// Export named exports (SystemJS style - no default property)
+module.exports = React;
+module.exports.useEffect = React.useEffect;
+module.exports.Component = React.Component;
+module.exports.Fragment = React.Fragment;
+module.exports.Profiler = React.Profiler;
+module.exports.useState = React.useState;
+module.exports.createElement = React.createElement;
diff --git a/test/configCases/target/system-default-import-fix/test.config.js b/test/configCases/target/system-default-import-fix/test.config.js
new file mode 100644
index 000000000..7d86e2c73
--- /dev/null
+++ b/test/configCases/target/system-default-import-fix/test.config.js
@@ -0,0 +1,27 @@
+"use strict";
+
+const path = require("path");
+
+/** @type {import("../../../../").Configuration} */
+module.exports = {
+	entry: "./test.js",
+	output: {
+		path: path.resolve(__dirname, "dist"),
+		filename: "bundle.js",
+		libraryTarget: "system"
+	},
+	externals: {
+		react: "react",
+		"react-with-default": "react-with-default"
+	},
+	resolve: {
+		alias: {
+			react: path.resolve(__dirname, "react.js"),
+			"react-with-default": path.resolve(__dirname, "react-with-default.js")
+		}
+	},
+	node: {
+		__dirname: false,
+		__filename: false
+	}
+};
diff --git a/test/configCases/target/system-default-import-fix/test.js b/test/configCases/target/system-default-import-fix/test.js
new file mode 100644
index 000000000..d01378be1
--- /dev/null
+++ b/test/configCases/target/system-default-import-fix/test.js
@@ -0,0 +1,36 @@
+import React, { useEffect } from "react";
+import ReactWithDefault, { useEffect as useEffectWithDefault } from "react-with-default";
+
+/* This test verifies that default imports work correctly with SystemJS externals
+ * in both scenarios:
+ * 1. External module without default property (traditional SystemJS)
+ * 2. External module with default property (ES6 module format)
+ */
+
+it("should correctly handle default import from SystemJS external without default property", function() {
+	// React should be the entire module object, not undefined
+	expect(React).toBeDefined();
+	expect(typeof React).toBe("object");
+	expect(React.Component).toBeDefined();
+	expect(React.Fragment).toBeDefined();
+	
+	// Named imports should still work
+	expect(typeof useEffect).toBe("function");
+	
+	// The default import should not be undefined
+	expect(React).not.toBeUndefined();
+});
+
+it("should correctly handle default import from SystemJS external with default property", function() {
+	// ReactWithDefault should be the default property value
+	expect(ReactWithDefault).toBeDefined();
+	expect(typeof ReactWithDefault).toBe("object");
+	expect(ReactWithDefault.Component).toBeDefined();
+	expect(ReactWithDefault.Fragment).toBeDefined();
+	
+	// Named imports should still work
+	expect(typeof useEffectWithDefault).toBe("function");
+	
+	// The default import should not be undefined
+	expect(ReactWithDefault).not.toBeUndefined();
+});
diff --git a/test/configCases/target/system-default-import-fix/webpack.config.js b/test/configCases/target/system-default-import-fix/webpack.config.js
new file mode 100644
index 000000000..2e66a663c
--- /dev/null
+++ b/test/configCases/target/system-default-import-fix/webpack.config.js
@@ -0,0 +1,15 @@
+"use strict";
+
+/** @type {import("../../../../").Configuration} */
+module.exports = {
+	output: {
+		libraryTarget: "system"
+	},
+	externals: {
+		react: "react"
+	},
+	node: {
+		__dirname: false,
+		__filename: false
+	}
+};