diff --git a/PhpcsChanged/CheckstyleReporter.php b/PhpcsChanged/CheckstyleReporter.php
new file mode 100644
index 0000000..00e345e
--- /dev/null
+++ b/PhpcsChanged/CheckstyleReporter.php
@@ -0,0 +1,75 @@
+<?php
+declare(strict_types=1);
+
+namespace PhpcsChanged;
+
+use PhpcsChanged\Reporter;
+use PhpcsChanged\PhpcsMessages;
+use PhpcsChanged\LintMessage;
+
+class CheckstyleReporter implements Reporter {
+	#[\Override]
+	public function getFormattedMessages(PhpcsMessages $messages, array $options): string { // phpcs:ignore VariableAnalysis.CodeAnalysis.VariableAnalysis.UnusedVariable
+		$files = array_unique(array_map(function(LintMessage $message): string {
+			return $message->getFile() ?? 'STDIN';
+		}, $messages->getMessages()));
+		if (count($files) === 0) {
+			$files = ['STDIN'];
+		}
+
+		$outputByFile = array_reduce($files, function(string $output, string $file) use ($messages): string {
+			$messagesForFile = array_values(array_filter($messages->getMessages(), static function(LintMessage $message) use ($file): bool {
+				return ($message->getFile() ?? 'STDIN') === $file;
+			}));
+			$output .= $this->getFormattedMessagesForFile($messagesForFile, $file);
+			return $output;
+		}, '');
+
+		$output = "<?xml version=\"1.0\" encoding=\"UTF-8\"?>\n";
+		$output .= "<checkstyle version=\"phpcs-changed-2.11.8\">\n";
+		$output .= $outputByFile;
+		$output .= "</checkstyle>\n";
+
+		return $output;
+	}
+
+	private function getFormattedMessagesForFile(array $messages, string $file): string {
+		if (count($messages) === 0) {
+			return '';
+		}
+
+		$xmlOutputForFile = "\t<file name=\"{$file}\">\n";
+		$xmlOutputForFile .= array_reduce($messages, function(string $output, LintMessage $message): string {
+			$line = $message->getLineNumber();
+			$column = $message->getColumn();
+			$source = $this->escapeXml($message->getSource());
+			$messageText = $this->escapeXml($message->getMessage());
+			$type = $message->getType();
+
+			// Map phpcs types to Checkstyle severity levels
+			$severity = $type === 'ERROR' ? 'error' : 'warning';
+
+			$output .= sprintf(
+				"\t\t<error line=\"%d\" column=\"%d\" severity=\"%s\" message=\"%s\" source=\"%s\"/>\n",
+				$line,
+				$column,
+				$severity,
+				$messageText,
+				$source
+			);
+			return $output;
+		}, '');
+		$xmlOutputForFile .= "\t</file>\n";
+
+		return $xmlOutputForFile;
+	}
+
+	private function escapeXml(string $string): string {
+		return htmlspecialchars($string, ENT_XML1 | ENT_QUOTES, 'UTF-8');
+	}
+
+	#[\Override]
+	public function getExitCode(PhpcsMessages $messages): int {
+		return (count($messages->getMessages()) > 0) ? 1 : 0;
+	}
+}
diff --git a/PhpcsChanged/Cli.php b/PhpcsChanged/Cli.php
index a677746..9ea650c 100644
--- a/PhpcsChanged/Cli.php
+++ b/PhpcsChanged/Cli.php
@@ -9,6 +9,7 @@
 use PhpcsChanged\JsonReporter;
 use PhpcsChanged\FullReporter;
 use PhpcsChanged\JunitReporter;
+use PhpcsChanged\CheckstyleReporter;
 use PhpcsChanged\PhpcsMessages;
 use PhpcsChanged\ShellException;
 use PhpcsChanged\ShellOperator;
@@ -144,7 +145,7 @@ function printHelp(): void {
 	printTwoColumns([
 		'--standard <STANDARD>' => 'The phpcs standard to use.',
 		'--extensions <EXTENSIONS>' => 'A comma separated list of extensions to check.',
-		'--report <REPORTER>' => 'The phpcs reporter to use. One of "full" (default), "json", "xml", or "junit".',
+		'--report <REPORTER>' => 'The phpcs reporter to use. One of "full" (default), "json", "xml", "junit", or "checkstyle".',
 		'-s' => 'Show sniff codes for each error when the reporter is "full".',
 		'--ignore <PATTERNS>' => 'A comma separated list of patterns to ignore files and directories.',
 		'--warning-severity' => 'The phpcs warning severity to report. See phpcs documentation for usage.',
@@ -194,6 +195,8 @@ function getReporter(string $reportType, CliOptions $options, ShellOperator $she
 			return new XmlReporter($options, $shell);
 		case 'junit':
 			return new JunitReporter();
+		case 'checkstyle':
+			return new CheckstyleReporter();
 	}
 	printErrorAndExit("Unknown Reporter '{$reportType}'");
 	throw new \Exception("Unknown Reporter '{$reportType}'"); // Just in case we don't exit for some reason.
diff --git a/README.md b/README.md
index 15f5a1d..9534d86 100644
--- a/README.md
+++ b/README.md
@@ -100,7 +100,7 @@ More than one file can be specified after a version control option, including gl
 
 You can use `--ignore` to ignore any directory, file, or paths matching provided pattern(s). For example.: `--ignore=bin/*,vendor/*` would ignore any files in bin directory, as well as in vendor.
 
-You can use `--report` to customize the output type. `full` (the default) is human-readable, `json` prints a JSON object as shown above, and 'xml' can be used by IDEs. These match the phpcs reporters of the same names. `junit` can also be used for [JUnit XML](https://github.com/testmoapp/junitxml) which can be helpful for test runners.
+You can use `--report` to customize the output type. `full` (the default) is human-readable, `json` prints a JSON object as shown above, and 'xml' can be used by IDEs. These match the phpcs reporters of the same names. `junit` can also be used for [JUnit XML](https://github.com/testmoapp/junitxml) which can be helpful for test runners. `checkstyle` will output Checkstyle format.
 
 You can use `--standard` to specify a specific phpcs standard to run. This matches the phpcs option of the same name.
 
diff --git a/index.php b/index.php
index 48486b9..a3986e5 100644
--- a/index.php
+++ b/index.php
@@ -19,6 +19,7 @@
 require_once __DIR__ . '/PhpcsChanged/FullReporter.php';
 require_once __DIR__ . '/PhpcsChanged/XmlReporter.php';
 require_once __DIR__ . '/PhpcsChanged/JunitReporter.php';
+require_once __DIR__ . '/PhpcsChanged/CheckstyleReporter.php';
 require_once __DIR__ . '/PhpcsChanged/NoChangesException.php';
 require_once __DIR__ . '/PhpcsChanged/ShellException.php';
 require_once __DIR__ . '/PhpcsChanged/ShellOperator.php';
diff --git a/tests/CheckstyleReporterTest.php b/tests/CheckstyleReporterTest.php
new file mode 100644
index 0000000..95c9e80
--- /dev/null
+++ b/tests/CheckstyleReporterTest.php
@@ -0,0 +1,247 @@
+<?php
+declare(strict_types=1);
+
+require_once dirname(__DIR__) . '/index.php';
+require_once __DIR__ . '/helpers/helpers.php';
+
+use PHPUnit\Framework\TestCase;
+use PhpcsChanged\PhpcsMessages;
+use PhpcsChanged\CheckstyleReporter;
+
+final class CheckstyleReporterTest extends TestCase {
+	public function testSingleWarning() {
+		$messages = PhpcsMessages::fromArrays([
+			[
+				'type' => 'WARNING',
+				'severity' => 5,
+				'fixable' => false,
+				'column' => 5,
+				'source' => 'ImportDetection.Imports.RequireImports.Import',
+				'line' => 15,
+				'message' => 'Found unused symbol Foo.',
+			],
+		], 'fileA.php');
+		$expected = <<<EOF
+<?xml version="1.0" encoding="UTF-8"?>
+<checkstyle version="phpcs-changed-2.11.8">
+	<file name="fileA.php">
+		<error line="15" column="5" severity="warning" message="Found unused symbol Foo." source="ImportDetection.Imports.RequireImports.Import"/>
+	</file>
+</checkstyle>
+
+EOF;
+		$reporter = new CheckstyleReporter();
+		$result = $reporter->getFormattedMessages($messages, []);
+		$this->assertEquals($expected, $result);
+	}
+
+	public function testSingleError() {
+		$messages = PhpcsMessages::fromArrays([
+			[
+				'type' => 'ERROR',
+				'severity' => 5,
+				'fixable' => false,
+				'column' => 5,
+				'source' => 'ImportDetection.Imports.RequireImports.Import',
+				'line' => 15,
+				'message' => 'Found unused symbol Foo.',
+			],
+		], 'fileA.php');
+		$expected = <<<EOF
+<?xml version="1.0" encoding="UTF-8"?>
+<checkstyle version="phpcs-changed-2.11.8">
+	<file name="fileA.php">
+		<error line="15" column="5" severity="error" message="Found unused symbol Foo." source="ImportDetection.Imports.RequireImports.Import"/>
+	</file>
+</checkstyle>
+
+EOF;
+		$reporter = new CheckstyleReporter();
+		$result = $reporter->getFormattedMessages($messages, []);
+		$this->assertEquals($expected, $result);
+	}
+
+	public function testMultipleWarningsWithLongLineNumber() {
+		$messages = PhpcsMessages::fromArrays([
+			[
+				'type' => 'WARNING',
+				'severity' => 5,
+				'fixable' => false,
+				'column' => 5,
+				'source' => 'ImportDetection.Imports.RequireImports.Import',
+				'line' => 133825,
+				'message' => 'Found unused symbol Foo.',
+			],
+			[
+				'type' => 'WARNING',
+				'severity' => 5,
+				'fixable' => false,
+				'column' => 5,
+				'source' => 'ImportDetection.Imports.RequireImports.Import',
+				'line' => 15,
+				'message' => 'Found unused symbol Bar.',
+			],
+		], 'fileA.php');
+		$expected = <<<EOF
+<?xml version="1.0" encoding="UTF-8"?>
+<checkstyle version="phpcs-changed-2.11.8">
+	<file name="fileA.php">
+		<error line="133825" column="5" severity="warning" message="Found unused symbol Foo." source="ImportDetection.Imports.RequireImports.Import"/>
+		<error line="15" column="5" severity="warning" message="Found unused symbol Bar." source="ImportDetection.Imports.RequireImports.Import"/>
+	</file>
+</checkstyle>
+
+EOF;
+		$reporter = new CheckstyleReporter();
+		$result = $reporter->getFormattedMessages($messages, []);
+		$this->assertEquals($expected, $result);
+	}
+
+	public function testMultipleWarningsErrorsAndFiles() {
+		$messagesA = PhpcsMessages::fromArrays([
+			[
+				'type' => 'ERROR',
+				'severity' => 5,
+				'fixable' => true,
+				'column' => 2,
+				'source' => 'ImportDetection.Imports.RequireImports.Something',
+				'line' => 12,
+				'message' => 'Found unused symbol Faa.',
+			],
+			[
+				'type' => 'ERROR',
+				'severity' => 5,
+				'fixable' => false,
+				'column' => 5,
+				'source' => 'ImportDetection.Imports.RequireImports.Import',
+				'line' => 15,
+				'message' => 'Found unused symbol Foo.',
+			],
+			[
+				'type' => 'WARNING',
+				'severity' => 5,
+				'fixable' => false,
+				'column' => 8,
+				'source' => 'ImportDetection.Imports.RequireImports.Boom',
+				'line' => 18,
+				'message' => 'Found unused symbol Bar.',
+			],
+		], 'fileA.php');
+		$messagesB = PhpcsMessages::fromArrays([
+			[
+				'type' => 'WARNING',
+				'severity' => 5,
+				'fixable' => false,
+				'column' => 5,
+				'source' => 'ImportDetection.Imports.RequireImports.Zoop',
+				'line' => 30,
+				'message' => 'Found unused symbol Hi.',
+			],
+		], 'fileB.php');
+		$messages = PhpcsMessages::merge([$messagesA, $messagesB]);
+		$expected = <<<EOF
+<?xml version="1.0" encoding="UTF-8"?>
+<checkstyle version="phpcs-changed-2.11.8">
+	<file name="fileA.php">
+		<error line="12" column="2" severity="error" message="Found unused symbol Faa." source="ImportDetection.Imports.RequireImports.Something"/>
+		<error line="15" column="5" severity="error" message="Found unused symbol Foo." source="ImportDetection.Imports.RequireImports.Import"/>
+		<error line="18" column="8" severity="warning" message="Found unused symbol Bar." source="ImportDetection.Imports.RequireImports.Boom"/>
+	</file>
+	<file name="fileB.php">
+		<error line="30" column="5" severity="warning" message="Found unused symbol Hi." source="ImportDetection.Imports.RequireImports.Zoop"/>
+	</file>
+</checkstyle>
+
+EOF;
+		$reporter = new CheckstyleReporter();
+		$result = $reporter->getFormattedMessages($messages, ['s' => 1]);
+		$this->assertEquals($expected, $result);
+	}
+
+	public function testNoWarnings() {
+		$messages = PhpcsMessages::fromArrays([]);
+		$expected = <<<EOF
+<?xml version="1.0" encoding="UTF-8"?>
+<checkstyle version="phpcs-changed-2.11.8">
+</checkstyle>
+
+EOF;
+		$reporter = new CheckstyleReporter();
+		$result = $reporter->getFormattedMessages($messages, []);
+		$this->assertEquals($expected, $result);
+	}
+
+	public function testSingleWarningWithNoFilename() {
+		$messages = PhpcsMessages::fromArrays([
+			[
+				'type' => 'WARNING',
+				'severity' => 5,
+				'fixable' => false,
+				'column' => 5,
+				'source' => 'ImportDetection.Imports.RequireImports.Import',
+				'line' => 15,
+				'message' => 'Found unused symbol Foo.',
+			],
+		]);
+		$expected = <<<EOF
+<?xml version="1.0" encoding="UTF-8"?>
+<checkstyle version="phpcs-changed-2.11.8">
+	<file name="STDIN">
+		<error line="15" column="5" severity="warning" message="Found unused symbol Foo." source="ImportDetection.Imports.RequireImports.Import"/>
+	</file>
+</checkstyle>
+
+EOF;
+		$reporter = new CheckstyleReporter();
+		$result = $reporter->getFormattedMessages($messages, []);
+		$this->assertEquals($expected, $result);
+	}
+
+	public function testXmlEscaping() {
+		$messages = PhpcsMessages::fromArrays([
+			[
+				'type' => 'ERROR',
+				'severity' => 5,
+				'fixable' => false,
+				'column' => 5,
+				'source' => 'Test.Source<>&"',
+				'line' => 15,
+				'message' => 'Message with <xml> & "quotes".',
+			],
+		], 'fileA.php');
+		$expected = <<<EOF
+<?xml version="1.0" encoding="UTF-8"?>
+<checkstyle version="phpcs-changed-2.11.8">
+	<file name="fileA.php">
+		<error line="15" column="5" severity="error" message="Message with &lt;xml&gt; &amp; &quot;quotes&quot;." source="Test.Source&lt;&gt;&amp;&quot;"/>
+	</file>
+</checkstyle>
+
+EOF;
+		$reporter = new CheckstyleReporter();
+		$result = $reporter->getFormattedMessages($messages, []);
+		$this->assertEquals($expected, $result);
+	}
+
+	public function testGetExitCodeWithMessages() {
+		$messages = PhpcsMessages::fromArrays([
+			[
+				'type' => 'WARNING',
+				'severity' => 5,
+				'fixable' => false,
+				'column' => 5,
+				'source' => 'ImportDetection.Imports.RequireImports.Import',
+				'line' => 15,
+				'message' => 'Found unused symbol Foo.',
+			],
+		], 'fileA.php');
+		$reporter = new CheckstyleReporter();
+		$this->assertEquals(1, $reporter->getExitCode($messages));
+	}
+
+	public function testGetExitCodeWithNoMessages() {
+		$messages = PhpcsMessages::fromArrays([], 'fileA.php');
+		$reporter = new CheckstyleReporter();
+		$this->assertEquals(0, $reporter->getExitCode($messages));
+	}
+}