diff --git a/src/Property/CSSNamespace.php b/src/Property/CSSNamespace.php
index 1801904a..6046bdf9 100644
--- a/src/Property/CSSNamespace.php
+++ b/src/Property/CSSNamespace.php
@@ -8,6 +8,7 @@
 use Sabberworm\CSS\OutputFormat;
 use Sabberworm\CSS\Position\Position;
 use Sabberworm\CSS\Position\Positionable;
+use Sabberworm\CSS\ShortClassNameProvider;
 use Sabberworm\CSS\Value\CSSString;
 use Sabberworm\CSS\Value\URL;
 
@@ -18,6 +19,7 @@ class CSSNamespace implements AtRule, Positionable
 {
     use CommentContainer;
     use Position;
+    use ShortClassNameProvider;
 
     /**
      * @var CSSString|URL
@@ -102,6 +104,11 @@ public function atRuleArgs(): array
      */
     public function getArrayRepresentation(): array
     {
-        throw new \BadMethodCallException('`getArrayRepresentation` is not yet implemented for `' . self::class . '`');
+        return [
+            'class' => $this->getShortClassName(),
+            // We're using `uri` here instead of `url` to better match the spec.
+            'uri' => $this->url->getArrayRepresentation(),
+            'prefix' => $this->prefix,
+        ];
     }
 }
diff --git a/tests/Unit/Property/CSSNamespaceTest.php b/tests/Unit/Property/CSSNamespaceTest.php
index 44f5c7d1..b00f4848 100644
--- a/tests/Unit/Property/CSSNamespaceTest.php
+++ b/tests/Unit/Property/CSSNamespaceTest.php
@@ -8,6 +8,7 @@
 use Sabberworm\CSS\CSSList\CSSListItem;
 use Sabberworm\CSS\Property\CSSNamespace;
 use Sabberworm\CSS\Value\CSSString;
+use Sabberworm\CSS\Value\URL;
 
 /**
  * @covers \Sabberworm\CSS\Property\CSSNamespace
@@ -35,10 +36,79 @@ public function implementsCSSListItem(): void
     /**
      * @test
      */
-    public function getArrayRepresentationThrowsException(): void
+    public function getArrayRepresentationIncludesClassName(): void
     {
-        $this->expectException(\BadMethodCallException::class);
+        $subject = new CSSNamespace(new CSSString('http://www.w3.org/2000/svg'));
 
-        $this->subject->getArrayRepresentation();
+        $result = $subject->getArrayRepresentation();
+
+        self::assertSame('CSSNamespace', $result['class']);
+    }
+
+    /**
+     * @test
+     */
+    public function getArrayRepresentationIncludesUrlProvidedAsCssString(): void
+    {
+        $uri = 'http://www.w3.org/2000/svg';
+        $subject = new CSSNamespace(new CSSString($uri));
+
+        $result = $subject->getArrayRepresentation();
+
+        self::assertSame(
+            [
+                'class' => 'CSSString',
+                'contents' => $uri,
+            ],
+            $result['uri']
+        );
+    }
+
+    /**
+     * @test
+     */
+    public function getArrayRepresentationIncludesUrlProvidedAsUrl(): void
+    {
+        $uri = 'http://www.w3.org/2000/svg';
+        $subject = new CSSNamespace(new URL(new CSSString($uri)));
+
+        $result = $subject->getArrayRepresentation();
+
+        self::assertSame(
+            [
+                'class' => 'URL',
+                'uri' => [
+                    'class' => 'CSSString',
+                    'contents' => $uri,
+                ],
+            ],
+            $result['uri']
+        );
+    }
+
+    /**
+     * @test
+     */
+    public function getArrayRepresentationIncludesPrefixForNullPrefix(): void
+    {
+        $subject = new CSSNamespace(new CSSString('http://www.w3.org/2000/svg'), null);
+
+        $result = $subject->getArrayRepresentation();
+
+        self::assertNull($result['prefix']);
+    }
+
+    /**
+     * @test
+     */
+    public function getArrayRepresentationIncludesPrefixForStringPrefix(): void
+    {
+        $prefix = 'hello';
+
+        $subject = new CSSNamespace(new CSSString('http://www.w3.org/2000/svg'), $prefix);
+
+        $result = $subject->getArrayRepresentation();
+
+        self::assertSame($prefix, $result['prefix']);
     }
 }