diff --git a/CHANGELOG.md b/CHANGELOG.md
index 172e8b4..4987633 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -31,3 +31,4 @@
 - Implement `xsd:decimal` codec
 - Implement `xsd:double` codec
 - Implement `xsd:float` codec
+- Implement `xsd:unsignedInt` codec
diff --git a/README.md b/README.md
index 3880167..01c9f73 100644
--- a/README.md
+++ b/README.md
@@ -44,7 +44,7 @@ This library aims to support the following XSD 1.1 built-in datatypes that are c
 | `xsd:nonNegativeInteger` |      ✅      |        ✅        |    `BigInt`    |     `dart:core`    |
 | `xsd:positiveInteger` |      ✅      |        ✅        |    `BigInt`    |     `dart:core`    |
 | `xsd:unsignedLong` |      ✅      |        ✅        |    `BigInt`    |     `dart:core`    |
-| `xsd:unsignedInt` |      ✅      |        ❌        |    `int`    |     `dart:core`    |
+| `xsd:unsignedInt` |      ✅      |        ✅        |    `int`    |     `dart:core`    |
 | `xsd:unsignedShort` |      ✅      |        ✅        |    `int`    |     `dart:core`    |
 | `xsd:unsignedByte` |      ✅      |        ✅        |    `int`    |     `dart:core`    |
 | `xsd:anyURI` |      ✅      |        ✅        |    `Uri`    |     `dart:core`    |
diff --git a/lib/src/codecs/unsigned_int/unsigned_int_codec.dart b/lib/src/codecs/unsigned_int/unsigned_int_codec.dart
new file mode 100644
index 0000000..28e5b62
--- /dev/null
+++ b/lib/src/codecs/unsigned_int/unsigned_int_codec.dart
@@ -0,0 +1,18 @@
+import 'dart:convert';
+
+import 'package:xsd/src/codecs/unsigned_int/unsigned_int_decoder.dart';
+import 'package:xsd/src/codecs/unsigned_int/unsigned_int_encoder.dart';
+
+/// A codec for xsd:unsignedInt.
+///
+/// Converts between a string representation of an unsigned integer and an
+/// [int].
+class XsdUnsignedIntCodec extends Codec<int, String> {
+  const XsdUnsignedIntCodec();
+
+  @override
+  Converter<String, int> get decoder => const XsdUnsignedIntDecoder();
+
+  @override
+  Converter<int, String> get encoder => const XsdUnsignedIntEncoder();
+}
diff --git a/lib/src/codecs/unsigned_int/unsigned_int_decoder.dart b/lib/src/codecs/unsigned_int/unsigned_int_decoder.dart
new file mode 100644
index 0000000..f2e0a8e
--- /dev/null
+++ b/lib/src/codecs/unsigned_int/unsigned_int_decoder.dart
@@ -0,0 +1,35 @@
+import 'dart:convert';
+import 'dart:typed_data';
+
+import '../../helpers/whitespace.dart';
+
+class XsdUnsignedIntDecoder extends Converter<String, int> {
+  const XsdUnsignedIntDecoder();
+
+  @override
+  int convert(String input) {
+    final str = processWhiteSpace(input, Whitespace.collapse);
+
+    if (str.isEmpty) {
+      throw const FormatException('The input string cannot be empty.');
+    }
+
+    final value = int.tryParse(str);
+
+    if (value == null) {
+      throw FormatException('The input "$str" is not a valid integer.');
+    }
+
+    // Use Uint32List to validate that the value fits within 32 bits (wraps on overflow).
+    final list = Uint32List(1);
+    list[0] = value;
+
+    if (list[0] != value) {
+      throw FormatException(
+        'The value "$value" is out of range for xsd:unsignedInt.',
+      );
+    }
+
+    return value;
+  }
+}
diff --git a/lib/src/codecs/unsigned_int/unsigned_int_encoder.dart b/lib/src/codecs/unsigned_int/unsigned_int_encoder.dart
new file mode 100644
index 0000000..f5b3212
--- /dev/null
+++ b/lib/src/codecs/unsigned_int/unsigned_int_encoder.dart
@@ -0,0 +1,21 @@
+import 'dart:convert';
+import 'dart:typed_data';
+
+/// A [Converter] that converts an [int] to an XSD `unsignedInt` string.
+class XsdUnsignedIntEncoder extends Converter<int, String> {
+  const XsdUnsignedIntEncoder();
+
+  @override
+  String convert(int input) {
+    // Use Uint32List to validate that the value fits within 32 bits (wraps on overflow).
+    final list = Uint32List(1);
+    list[0] = input;
+    if (list[0] != input) {
+      throw FormatException(
+        'The value "$input" is out of range for xsd:unsignedInt.',
+      );
+    }
+
+    return input.toString();
+  }
+}
diff --git a/test/codecs/unsigned_int_codec_test.dart b/test/codecs/unsigned_int_codec_test.dart
new file mode 100644
index 0000000..5ce3af3
--- /dev/null
+++ b/test/codecs/unsigned_int_codec_test.dart
@@ -0,0 +1,28 @@
+import 'package:test/test.dart';
+import 'package:xsd/src/codecs/unsigned_int/unsigned_int_codec.dart';
+
+void main() {
+  test('XSD Unsigned Int Codec -> Decode', () {
+    const codec = XsdUnsignedIntCodec();
+    final decoder = codec.decoder;
+
+    expect(decoder.convert('12345'), equals(12345));
+    expect(decoder.convert('0'), equals(0));
+    expect(decoder.convert('4294967295'), equals(4294967295));
+    expect(() => decoder.convert('-1'), throwsFormatException);
+    expect(() => decoder.convert('4294967296'), throwsFormatException);
+    expect(() => decoder.convert('abc'), throwsFormatException);
+    expect(() => decoder.convert(''), throwsFormatException);
+  });
+
+  test('XSD Unsigned Int Codec -> Encode', () {
+    const codec = XsdUnsignedIntCodec();
+    final encoder = codec.encoder;
+
+    expect(encoder.convert(12345), equals('12345'));
+    expect(encoder.convert(0), equals('0'));
+    expect(encoder.convert(4294967295), equals('4294967295'));
+    expect(() => encoder.convert(-1), throwsFormatException);
+    expect(() => encoder.convert(4294967296), throwsFormatException);
+  });
+}