diff --git a/src/Analyze/RuleProcessor/MetafileProcessor/MissingECSSetsMetafileProcessor.php b/src/Analyze/RuleProcessor/MetafileProcessor/MissingECSSetsMetafileProcessor.php
new file mode 100644
index 0000000..94d0341
--- /dev/null
+++ b/src/Analyze/RuleProcessor/MetafileProcessor/MissingECSSetsMetafileProcessor.php
@@ -0,0 +1,66 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Rector\Monitor\Analyze\RuleProcessor\MetafileProcessor;
+
+use Rector\Monitor\Analyze\Contract\RuleProcessorInterface;
+use Rector\Monitor\Analyze\Reporting\ErrorCollector;
+use Rector\Monitor\Config\MonitorConfig;
+use Rector\Monitor\ValueObject\ComposerJson;
+
+/**
+ * @see \Rector\Monitor\Tests\Analyze\RuleProcessor\MetafileProcessor\MissingECSSetsMetafileProcessor\MissingECSSetsMetafileProcessorTest
+ */
+final readonly class MissingECSSetsMetafileProcessor implements RuleProcessorInterface
+{
+    public function process(
+        MonitorConfig $monitorConfig,
+        ComposerJson $composerJson,
+        ErrorCollector $errorCollector
+    ): void {
+        $requiredECSSets = $monitorConfig->getRequiredECSSets();
+        if ($requiredECSSets === []) {
+            return;
+        }
+
+        foreach ($monitorConfig->getRepositoryCollection()->all() as $repository) {
+            foreach ($repository->getRootFiles() as $repositoryRootFile) {
+                if ($repositoryRootFile->getFilename() !== 'ecs.php') {
+                    continue;
+                }
+
+                $configuredECSSets = $this->resolveConfiguredECSSets($repositoryRootFile->getContents());
+
+                foreach ($requiredECSSets as $requiredECSSet) {
+                    if (in_array($requiredECSSet, $configuredECSSets, true)) {
+                        continue;
+                    }
+
+                    $errorCollector->addErrorMessage(sprintf(
+                        ' * ECS set "<fg=yellow>%s</>" is <fg=red>missing</> in "<fg=green>%s</>". Add it via "->withPreparedSets(%s: true)"',
+                        $requiredECSSet,
+                        $repositoryRootFile->getFilename(),
+                        $requiredECSSet
+                    ));
+                }
+            }
+        }
+    }
+
+    /**
+     * @return string[]
+     */
+    private function resolveConfiguredECSSets(string $ecsContents): array
+    {
+        if (preg_match('#withPreparedSets\s*\((?<arguments>[^)]*)\)#s', $ecsContents, $match) !== 1) {
+            return [];
+        }
+
+        if (preg_match_all('#(?<name>\w+)\s*:\s*true\b#', $match['arguments'], $argumentMatches) === false) {
+            return [];
+        }
+
+        return $argumentMatches['name'];
+    }
+}
diff --git a/src/Config/MonitorConfig.php b/src/Config/MonitorConfig.php
index 866d8f5..98d5cdd 100644
--- a/src/Config/MonitorConfig.php
+++ b/src/Config/MonitorConfig.php
@@ -36,6 +36,11 @@ final class MonitorConfig
      */
     private array $minPackagesVersions = [];
 
+    /**
+     * @var string[]
+     */
+    private array $requiredECSSets = [];
+
     private bool $noPHPStanBaseline = false;
 
     private ?int $minPHPStanLevel = null;
@@ -169,6 +174,27 @@ public function getMinPHPStanLevel(): ?int
         return $this->minPHPStanLevel;
     }
 
+    /**
+     * @api to be used
+     * @param string[] $ecsSetNames
+     */
+    public function requireECSSets(array $ecsSetNames): self
+    {
+        Assert::allString($ecsSetNames);
+
+        $this->requiredECSSets = array_merge($this->requiredECSSets, $ecsSetNames);
+
+        return $this;
+    }
+
+    /**
+     * @return string[]
+     */
+    public function getRequiredECSSets(): array
+    {
+        return $this->requiredECSSets;
+    }
+
     /**
      * @return string[]
      */
diff --git a/tests/Analyze/RuleProcessor/MetafileProcessor/MissingECSSetsMetafileProcessor/Fixture/with-psr12/ecs.php b/tests/Analyze/RuleProcessor/MetafileProcessor/MissingECSSetsMetafileProcessor/Fixture/with-psr12/ecs.php
new file mode 100644
index 0000000..0785696
--- /dev/null
+++ b/tests/Analyze/RuleProcessor/MetafileProcessor/MissingECSSetsMetafileProcessor/Fixture/with-psr12/ecs.php
@@ -0,0 +1,9 @@
+<?php
+
+declare(strict_types=1);
+
+use Symplify\EasyCodingStandard\Config\ECSConfig;
+
+return ECSConfig::configure()
+    ->withPaths([__DIR__ . '/src'])
+    ->withPreparedSets(psr12: true);
diff --git a/tests/Analyze/RuleProcessor/MetafileProcessor/MissingECSSetsMetafileProcessor/Fixture/without-psr12/ecs.php b/tests/Analyze/RuleProcessor/MetafileProcessor/MissingECSSetsMetafileProcessor/Fixture/without-psr12/ecs.php
new file mode 100644
index 0000000..b3f2545
--- /dev/null
+++ b/tests/Analyze/RuleProcessor/MetafileProcessor/MissingECSSetsMetafileProcessor/Fixture/without-psr12/ecs.php
@@ -0,0 +1,9 @@
+<?php
+
+declare(strict_types=1);
+
+use Symplify\EasyCodingStandard\Config\ECSConfig;
+
+return ECSConfig::configure()
+    ->withPaths([__DIR__ . '/src'])
+    ->withPreparedSets(common: true);
diff --git a/tests/Analyze/RuleProcessor/MetafileProcessor/MissingECSSetsMetafileProcessor/MissingECSSetsMetafileProcessorTest.php b/tests/Analyze/RuleProcessor/MetafileProcessor/MissingECSSetsMetafileProcessor/MissingECSSetsMetafileProcessorTest.php
new file mode 100644
index 0000000..b959660
--- /dev/null
+++ b/tests/Analyze/RuleProcessor/MetafileProcessor/MissingECSSetsMetafileProcessor/MissingECSSetsMetafileProcessorTest.php
@@ -0,0 +1,85 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Rector\Monitor\Tests\Analyze\RuleProcessor\MetafileProcessor\MissingECSSetsMetafileProcessor;
+
+use Override;
+use Rector\Monitor\Analyze\Reporting\ErrorCollector;
+use Rector\Monitor\Analyze\RuleProcessor\MetafileProcessor\MissingECSSetsMetafileProcessor;
+use Rector\Monitor\Config\MonitorConfig;
+use Rector\Monitor\Tests\AbstractTestCase;
+use Rector\Monitor\ValueObject\ComposerJson;
+use Symfony\Component\Finder\SplFileInfo;
+
+final class MissingECSSetsMetafileProcessorTest extends AbstractTestCase
+{
+    private MissingECSSetsMetafileProcessor $missingECSSetsMetafileProcessor;
+
+    #[Override]
+    protected function setUp(): void
+    {
+        parent::setUp();
+
+        $this->missingECSSetsMetafileProcessor = $this->make(MissingECSSetsMetafileProcessor::class);
+    }
+
+    public function testReportsMissingSet(): void
+    {
+        $monitorConfig = $this->createMonitorConfigWithRepository(__DIR__ . '/Fixture/without-psr12/ecs.php');
+        $monitorConfig->requireECSSets(['psr12']);
+
+        $errorCollector = new ErrorCollector();
+        $this->missingECSSetsMetafileProcessor->process(
+            $monitorConfig,
+            new ComposerJson('https://example.com/some/repo.git', []),
+            $errorCollector
+        );
+
+        $errorMessages = $errorCollector->getErrorMessages();
+        $this->assertCount(1, $errorMessages);
+        $this->assertStringContainsString('psr12', $errorMessages[0]);
+        $this->assertStringContainsString('missing', $errorMessages[0]);
+    }
+
+    public function testSkipsWhenSetIsConfigured(): void
+    {
+        $monitorConfig = $this->createMonitorConfigWithRepository(__DIR__ . '/Fixture/with-psr12/ecs.php');
+        $monitorConfig->requireECSSets(['psr12']);
+
+        $errorCollector = new ErrorCollector();
+        $this->missingECSSetsMetafileProcessor->process(
+            $monitorConfig,
+            new ComposerJson('https://example.com/some/repo.git', []),
+            $errorCollector
+        );
+
+        $this->assertEmpty($errorCollector->getErrorMessages());
+    }
+
+    public function testSkipsWhenNoRequiredSetsConfigured(): void
+    {
+        $monitorConfig = $this->createMonitorConfigWithRepository(__DIR__ . '/Fixture/without-psr12/ecs.php');
+
+        $errorCollector = new ErrorCollector();
+        $this->missingECSSetsMetafileProcessor->process(
+            $monitorConfig,
+            new ComposerJson('https://example.com/some/repo.git', []),
+            $errorCollector
+        );
+
+        $this->assertEmpty($errorCollector->getErrorMessages());
+    }
+
+    private function createMonitorConfigWithRepository(string $ecsConfigPath): MonitorConfig
+    {
+        $monitorConfig = new MonitorConfig();
+        $monitorConfig->addRepositories(['https://example.com/some/repo.git']);
+
+        $repository = $monitorConfig->getRepositoryCollection()
+            ->all()[0];
+        $repository->decorateRootFiles([new SplFileInfo($ecsConfigPath, '', 'ecs.php')]);
+
+        return $monitorConfig;
+    }
+}