diff --git a/composer.json b/composer.json
index 19cc1ac..452bc77 100644
--- a/composer.json
+++ b/composer.json
@@ -2,7 +2,7 @@
     "name": "programmatordev/yet-another-php-validator",
     "description": "PHP validator with expressive error messages",
     "type": "library",
-    "keywords": ["PHP", "PHP8", "Validator", "Validation"],
+    "keywords": ["php", "php8", "validator", "validation"],
     "license": "MIT",
     "authors": [
         {
@@ -14,13 +14,14 @@
     "require": {
         "php": ">=8.1",
         "egulias/email-validator": "^4.0",
-        "symfony/intl": "^6.3",
+        "symfony/intl": "^6.4",
         "symfony/polyfill-ctype": "^1.27",
-        "symfony/polyfill-intl-grapheme": "^1.29"
+        "symfony/polyfill-intl-grapheme": "^1.29",
+        "symfony/polyfill-intl-icu": "^1.29"
     },
     "require-dev": {
         "phpunit/phpunit": "^10.0",
-        "symfony/var-dumper": "^6.3"
+        "symfony/var-dumper": "^6.4"
     },
     "autoload": {
         "psr-4": {
diff --git a/docs/03-rules.md b/docs/03-rules.md
index 944b879..f127121 100644
--- a/docs/03-rules.md
+++ b/docs/03-rules.md
@@ -40,6 +40,7 @@
 - [Choice](03-rules_choice.md)
 - [Country](03-rules_country.md)
 - [Language](03-rules_language.md)
+- [Locale](03-rules_locale.md)
 
 ## Iterable Rules
 
diff --git a/docs/03-rules_locale.md b/docs/03-rules_locale.md
new file mode 100644
index 0000000..6c76743
--- /dev/null
+++ b/docs/03-rules_locale.md
@@ -0,0 +1,56 @@
+# Locale
+
+Validates that a value is a valid locale code.
+
+```php
+Locale(
+    bool $canonicalize = false,
+    ?string $message = null
+);
+```
+
+## Basic Usage
+
+```php
+// by default, code should be the language code (pt, en, ...)
+// or the language code followed by an underscore and the uppercased country code (pt_PT, en_US, ...)
+Validator::locale()->validate('pt'); // true
+Validator::locale()->validate('pt_PT'); // true
+Validator::locale()->validate('pt_pt'); // false
+Validator::locale()->validate('pt-PT'); // false
+Validator::locale()->validate('pt_PRT'); // false
+
+// canonicalize value before validation
+Validator::language(canonicalize: true)->validate('pt_pt'); // true
+Validator::language(canonicalize: true)->validate('pt-PT'); // true
+Validator::language(canonicalize: true)->validate('pt_PRT'); // true
+Validator::language(canonicalize: true)->validate('PT-pt.utf8'); // true
+```
+
+> [!NOTE]
+> An `UnexpectedValueException` will be thrown when the input value is not a `string`.
+
+## Options
+
+### `canonicalize`
+
+type: `bool` default: `false`
+
+If `true`, the input value will be normalized before validation, according to the following [documentation](https://unicode-org.github.io/icu/userguide/locale/#canonicalization).
+
+### `message`
+
+type: `?string` default: `The {{ name }} value is not a valid locale, {{ value }} given.`
+
+Message that will be shown if the input value is not a valid locale code.
+
+The following parameters are available:
+
+| Parameter     | Description               |
+|---------------|---------------------------|
+| `{{ value }}` | The current invalid value |
+| `{{ name }}`  | Name of the invalid value |
+
+## Changelog
+
+- `1.1.0` Created
\ No newline at end of file
diff --git a/src/ChainedValidatorInterface.php b/src/ChainedValidatorInterface.php
index 10995de..c6c11bc 100644
--- a/src/ChainedValidatorInterface.php
+++ b/src/ChainedValidatorInterface.php
@@ -97,6 +97,11 @@ public function lessThanOrEqual(
         ?string $message = null
     ): ChainedValidatorInterface&Validator;
 
+    public function locale(
+        bool $canonicalize = false,
+        ?string $message = null
+    ): ChainedValidatorInterface&Validator;
+
     public function notBlank(
         ?callable $normalizer = null,
         ?string $message = null
diff --git a/src/Exception/LocaleException.php b/src/Exception/LocaleException.php
new file mode 100644
index 0000000..20531af
--- /dev/null
+++ b/src/Exception/LocaleException.php
@@ -0,0 +1,5 @@
+<?php
+
+namespace ProgrammatorDev\Validator\Exception;
+
+class LocaleException extends ValidationException {}
\ No newline at end of file
diff --git a/src/Rule/Locale.php b/src/Rule/Locale.php
new file mode 100644
index 0000000..dc6e506
--- /dev/null
+++ b/src/Rule/Locale.php
@@ -0,0 +1,44 @@
+<?php
+
+namespace ProgrammatorDev\Validator\Rule;
+
+use ProgrammatorDev\Validator\Exception\LocaleException;
+use ProgrammatorDev\Validator\Exception\UnexpectedTypeException;
+use Symfony\Component\Intl\Locales;
+
+class Locale extends AbstractRule implements RuleInterface
+{
+    private string $message = 'The {{ name }} value is not a valid locale, {{ value }} given.';
+
+    public function __construct(
+        private readonly bool $canonicalize = false,
+        ?string $message = null
+    )
+    {
+        $this->message = $message ?? $this->message;
+    }
+
+    public function assert(mixed $value, ?string $name = null): void
+    {
+        if (!\is_string($value)) {
+            throw new UnexpectedTypeException('string', get_debug_type($value));
+        }
+
+        // keep original value for parameters
+        $input = $value;
+
+        if ($this->canonicalize) {
+            $input = \Locale::canonicalize($input);
+        }
+
+        if (!Locales::exists($input)) {
+            throw new LocaleException(
+                message: $this->message,
+                parameters: [
+                    'name' => $name,
+                    'value' => $value
+                ]
+            );
+        }
+    }
+}
\ No newline at end of file
diff --git a/src/StaticValidatorInterface.php b/src/StaticValidatorInterface.php
index 154db90..74d0992 100644
--- a/src/StaticValidatorInterface.php
+++ b/src/StaticValidatorInterface.php
@@ -96,6 +96,11 @@ public static function lessThanOrEqual(
         ?string $message = null
     ): ChainedValidatorInterface&Validator;
 
+    public static function locale(
+        bool $canonicalize = false,
+        ?string $message = null
+    ): ChainedValidatorInterface&Validator;
+
     public static function notBlank(
         ?callable $normalizer = null,
         ?string $message = null
diff --git a/tests/LocaleTest.php b/tests/LocaleTest.php
new file mode 100644
index 0000000..932fe1f
--- /dev/null
+++ b/tests/LocaleTest.php
@@ -0,0 +1,56 @@
+<?php
+
+namespace ProgrammatorDev\Validator\Test;
+
+use ProgrammatorDev\Validator\Exception\LocaleException;
+use ProgrammatorDev\Validator\Rule\Locale;
+use ProgrammatorDev\Validator\Test\Util\TestRuleFailureConditionTrait;
+use ProgrammatorDev\Validator\Test\Util\TestRuleMessageOptionTrait;
+use ProgrammatorDev\Validator\Test\Util\TestRuleSuccessConditionTrait;
+use ProgrammatorDev\Validator\Test\Util\TestRuleUnexpectedValueTrait;
+
+class LocaleTest extends AbstractTest
+{
+    use TestRuleUnexpectedValueTrait;
+    use TestRuleFailureConditionTrait;
+    use TestRuleSuccessConditionTrait;
+    use TestRuleMessageOptionTrait;
+
+    public static function provideRuleUnexpectedValueData(): \Generator
+    {
+        $unexpectedTypeMessage = '/Expected value of type "string", (.*) given\./';
+
+        yield 'invalid type' => [new Locale(), 123, $unexpectedTypeMessage];
+    }
+
+    public static function provideRuleFailureConditionData(): \Generator
+    {
+        $exception = LocaleException::class;
+        $message = '/The (.*) value is not a valid locale, (.*) given\./';
+
+        yield 'invalid' => [new Locale(), 'invalid', $exception, $message];
+        yield 'uncanonicalized 1' => [new Locale(), 'pt_pt', $exception, $message];
+        yield 'uncanonicalized 2' => [new Locale(), 'pt-PT', $exception, $message];
+        yield 'uncanonicalized 3' => [new Locale(), 'PT-pt.utf8', $exception, $message];
+    }
+
+    public static function provideRuleSuccessConditionData(): \Generator
+    {
+        yield 'language code' => [new Locale(), 'pt'];
+        yield 'language and country code' => [new Locale(), 'pt_PT'];
+        yield 'canonicalized 1' => [new Locale(canonicalize: true), 'pt_pt'];
+        yield 'canonicalized 2' => [new Locale(canonicalize: true), 'pt-PT'];
+        yield 'canonicalized 3' => [new Locale(canonicalize: true), 'PT-pt.utf8'];
+    }
+
+    public static function provideRuleMessageOptionData(): \Generator
+    {
+        yield 'message' => [
+            new Locale(
+                message: '{{ name }} {{ value }}'
+            ),
+            'invalid',
+            'test "invalid"'
+        ];
+    }
+}
\ No newline at end of file