diff --git a/composer.json b/composer.json
index f8f6cc6..6182971 100644
--- a/composer.json
+++ b/composer.json
@@ -15,15 +15,15 @@
     "require-dev": {
         "brainbits/phpcs-standard": "^8.0.0",
         "brainbits/phpstan-rules": "^4.0.0",
-        "ergebnis/composer-normalize": "^2.47",
-        "ergebnis/phpstan-rules": "^2.11.0",
-        "phpstan/phpstan": "^2.1.22",
-        "phpstan/phpstan-phpunit": "^2.0.7",
-        "phpstan/phpstan-strict-rules": "^2.0.6",
-        "phpunit/phpunit": "^12.3.6",
-        "rector/rector": "^2.1.4",
-        "squizlabs/php_codesniffer": "^3.13.2",
-        "thecodingmachine/phpstan-safe-rule": "^1.4.1"
+        "ergebnis/composer-normalize": "^2.50",
+        "ergebnis/phpstan-rules": "^2.13.1",
+        "phpstan/phpstan": "^2.1.40",
+        "phpstan/phpstan-phpunit": "^2.0.16",
+        "phpstan/phpstan-strict-rules": "^2.0.10",
+        "phpunit/phpunit": "^12.5.14",
+        "rector/rector": "^2.3.8",
+        "squizlabs/php_codesniffer": "^3.13.5",
+        "thecodingmachine/phpstan-safe-rule": "^1.4.3"
     },
     "autoload": {
         "psr-4": {
diff --git a/src/NotConvertable.php b/src/NotConvertable.php
index b3ab85f..d3dd696 100644
--- a/src/NotConvertable.php
+++ b/src/NotConvertable.php
@@ -38,6 +38,11 @@ public static function toDateTime(mixed $value): self
         return self::withMessage(sprintf('%s is not convertable to date time object', get_debug_type($value)));
     }
 
+    public static function toDateTimeZone(mixed $value): self
+    {
+        return self::withMessage(sprintf('%s is not convertable to date time zone', get_debug_type($value)));
+    }
+
     private static function withMessage(string $message): self
     {
         $me = new self($message);
diff --git a/src/TypeGuard.php b/src/TypeGuard.php
index c8dacd6..e727b09 100644
--- a/src/TypeGuard.php
+++ b/src/TypeGuard.php
@@ -118,19 +118,20 @@ public function asString(mixed $value): string|null
         return (string) $value;
     }
 
-    /** @return DateTimeImmutable */
-    public function asDateTimeImmutable(mixed $value): DateTimeImmutable|null
+    public function asDateTimeImmutable(mixed $value, DateTimeZone|string|null $timeZone = null): DateTimeImmutable|null
     {
         if ($value === null) {
             return null;
         }
 
+        $timeZone = $this->asDateTimeZone($timeZone) ?? $this->timeZone();
+
         if ($value instanceof DateTimeImmutable) {
-            if ($value->getTimezone()->getName() === $this->timeZone()->getName()) {
+            if ($value->getTimezone()->getName() === $timeZone->getName()) {
                 return $value;
             }
 
-            return $value->setTimezone($this->timeZone());
+            return $value->setTimezone($timeZone);
         }
 
         if ($value instanceof Stringable) {
@@ -141,7 +142,29 @@ public function asDateTimeImmutable(mixed $value): DateTimeImmutable|null
             throw NotConvertable::toDateTime($value);
         }
 
-        return new DateTimeImmutable(asString($value), $this->timeZone());
+        return new DateTimeImmutable(asString($value), $timeZone);
+    }
+
+    /** @return ($value is null ? null : DateTimeZone) */
+    public function asDateTimeZone(mixed $value): DateTimeZone|null
+    {
+        if ($value === null) {
+            return null;
+        }
+
+        if ($value instanceof DateTimeZone) {
+            return $value;
+        }
+
+        if ($value instanceof Stringable) {
+            $value = (string) $value;
+        }
+
+        if (!is_string($value)) {
+            throw NotConvertable::toDateTimeZone($value);
+        }
+
+        return new DateTimeZone($value);
     }
 
     /** @return ($value is null ? null : string) */
diff --git a/src/functions.php b/src/functions.php
index e82f5fb..39ef983 100644
--- a/src/functions.php
+++ b/src/functions.php
@@ -5,6 +5,7 @@
 namespace Plook\TypeGuard;
 
 use DateTimeImmutable;
+use DateTimeZone;
 
 use function function_exists;
 
@@ -49,9 +50,20 @@ function asString(mixed $value): string|null
 if (!function_exists('\Plook\TypeGuard\asDateTimeImmutable')) { // @codeCoverageIgnore
 
     /** @return ($value is null ? null : DateTimeImmutable) */
-    function asDateTimeImmutable(mixed $value): DateTimeImmutable|null
+    function asDateTimeImmutable(
+        mixed $value,
+        DateTimeZone|string|null $timeZone = null,
+    ): DateTimeImmutable|null {
+        return TypeGuard::instance()->asDateTimeImmutable($value, $timeZone);
+    }
+}
+
+if (!function_exists('\Plook\TypeGuard\asDateTimeZone')) { // @codeCoverageIgnore
+
+    /** @return ($value is null ? null : DateTimeZone) */
+    function asDateTimeZone(mixed $value): DateTimeZone|null
     {
-        return TypeGuard::instance()->asDateTimeImmutable($value);
+        return TypeGuard::instance()->asDateTimeZone($value);
     }
 }
 
diff --git a/tests/AsDateTimeImmutableTest.php b/tests/AsDateTimeImmutableTest.php
index 531959e..4f1f251 100644
--- a/tests/AsDateTimeImmutableTest.php
+++ b/tests/AsDateTimeImmutableTest.php
@@ -94,6 +94,63 @@ public function testDoesNotTouchNull(): void
         self::assertNull(asDateTimeImmutable(null));
     }
 
+    public function testTimezoneParameterOverridesDefaultWithDateTimeZone(): void
+    {
+        $result = asDateTimeImmutable('2010-09-08 07:06:05', new DateTimeZone('Australia/Adelaide'));
+
+        self::assertInstanceOf(DateTimeImmutable::class, $result);
+        self::assertSame('2010-09-08T07:06:05+09:30', $result->format('c'));
+    }
+
+    public function testTimezoneParameterOverridesDefaultWithString(): void
+    {
+        $result = asDateTimeImmutable('2010-09-08 07:06:05', 'Australia/Adelaide');
+
+        self::assertInstanceOf(DateTimeImmutable::class, $result);
+        self::assertSame('2010-09-08T07:06:05+09:30', $result->format('c'));
+    }
+
+    public function testTimezoneParameterOverridesChangedDefault(): void
+    {
+        TypeGuard::instance()->timeZone('Europe/Berlin');
+
+        $result = asDateTimeImmutable('2010-09-08 07:06:05', 'Australia/Adelaide');
+
+        self::assertInstanceOf(DateTimeImmutable::class, $result);
+        self::assertSame('2010-09-08T07:06:05+09:30', $result->format('c'));
+    }
+
+    public function testTimezoneParameterConvertsSameDateTimeImmutable(): void
+    {
+        $input = new DateTimeImmutable('2010-09-08T07:06:05', new DateTimeZone('Australia/Adelaide'));
+
+        $result = asDateTimeImmutable($input, 'Australia/Adelaide');
+
+        self::assertInstanceOf(DateTimeImmutable::class, $result);
+        self::assertSame('Australia/Adelaide', $result->getTimezone()->getName());
+        self::assertSame('2010-09-08T07:06:05+09:30', $result->format('c'));
+    }
+
+    public function testTimezoneParameterConvertsDifferentDateTimeImmutable(): void
+    {
+        $input = new DateTimeImmutable('2010-09-08T07:06:05+00:00');
+
+        $result = asDateTimeImmutable($input, new DateTimeZone('Australia/Adelaide'));
+
+        self::assertInstanceOf(DateTimeImmutable::class, $result);
+        self::assertSame('2010-09-08T16:36:05+09:30', $result->format('c'));
+    }
+
+    public function testNullTimezoneParameterUsesDefault(): void
+    {
+        TypeGuard::instance()->timeZone('Australia/Adelaide');
+
+        $result = asDateTimeImmutable('2010-09-08 07:06:05');
+
+        self::assertInstanceOf(DateTimeImmutable::class, $result);
+        self::assertSame('2010-09-08T07:06:05+09:30', $result->format('c'));
+    }
+
     public function testOnlyScalarsAreConvertable(): void
     {
         $this->expectException(NotConvertable::class);
diff --git a/tests/AsDateTimeZoneTest.php b/tests/AsDateTimeZoneTest.php
new file mode 100644
index 0000000..100bd44
--- /dev/null
+++ b/tests/AsDateTimeZoneTest.php
@@ -0,0 +1,67 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Plook\Tests\TypeGuard;
+
+use DateTimeZone;
+use PHPUnit\Framework\Attributes\CoversClass;
+use PHPUnit\Framework\Attributes\CoversFunction;
+use PHPUnit\Framework\TestCase;
+use Plook\Tests\TypeGuard\Helper\StringableString;
+use Plook\TypeGuard\NotConvertable;
+use Plook\TypeGuard\TypeGuard;
+
+use function basename;
+use function Plook\TypeGuard\asDateTimeZone;
+use function sprintf;
+
+#[CoversClass(TypeGuard::class)]
+#[CoversClass(NotConvertable::class)]
+#[CoversFunction('Plook\TypeGuard\asDateTimeZone')]
+final class AsDateTimeZoneTest extends TestCase
+{
+    public function testConvertsStrings(): void
+    {
+        $dateTimeZone = asDateTimeZone('Europe/Berlin');
+
+        self::assertInstanceOf(DateTimeZone::class, $dateTimeZone);
+        self::assertSame('Europe/Berlin', $dateTimeZone->getName());
+    }
+
+    public function testConvertsStringables(): void
+    {
+        $dateTimeZone = asDateTimeZone(new StringableString('Australia/Adelaide'));
+
+        self::assertInstanceOf(DateTimeZone::class, $dateTimeZone);
+        self::assertSame('Australia/Adelaide', $dateTimeZone->getName());
+    }
+
+    public function testReturnsSameDateTimeZone(): void
+    {
+        $dateTimeZone = new DateTimeZone('Europe/Berlin');
+
+        $result = asDateTimeZone($dateTimeZone);
+
+        self::assertSame($dateTimeZone, $result);
+    }
+
+    public function testDoesNotTouchNull(): void
+    {
+        self::assertNull(asDateTimeZone(null));
+    }
+
+    public function testOnlyStringsAreConvertable(): void
+    {
+        $this->expectException(NotConvertable::class);
+        $this->expectExceptionMessageMatches(
+            sprintf(
+                '/Closure is not convertable to date time zone in %s:%s/',
+                basename(__FILE__),
+                __LINE__ + 4,
+            ),
+        );
+
+        asDateTimeZone(static fn (): null => null);
+    }
+}