diff --git a/src/Configuration/ECSConfigBuilder.php b/src/Configuration/ECSConfigBuilder.php
index c3647418d6..df1f622571 100644
--- a/src/Configuration/ECSConfigBuilder.php
+++ b/src/Configuration/ECSConfigBuilder.php
@@ -319,16 +319,9 @@ public function withPreparedSets(
      */
     public function withPhpCsFixerSets(bool ...$sets): self
     {
-        // config file is required twice (container build + cache hash), warn only once per process
-        static $warned = false;
-        if (! $warned) {
-            $warned = true;
-
-            $outputPrinter = new OutputPrinter(new OutputColorizer());
-            $outputPrinter->warning(
-                'The "withPhpCsFixerSets()" method is deprecated. Use ->withPreparedSets() or ->withSets() with prepared sets instead.'
-            );
-        }
+        $this->printDeprecationWarning(
+            'The "withPhpCsFixerSets()" method is deprecated. Use ->withPreparedSets() or ->withSets() with prepared sets instead.'
+        );
 
         return $this;
     }
@@ -376,8 +369,7 @@ public function withCache(?string $directory = null, ?string $namespace = null):
      */
     public function withEditorConfig(): self
     {
-        $outputPrinter = new OutputPrinter(new OutputColorizer());
-        $outputPrinter->warning(
+        $this->printDeprecationWarning(
             'The "withEditorConfig()" method is deprecated, as it leaks project-wide settings into ECS. Configure the matching PHP-CS-Fixer rules explicitly instead.'
         );
         return $this;
@@ -439,13 +431,33 @@ public function withoutParallel(): self
      */
     public function withRealPathReporting(): self
     {
-        $outputPrinter = new OutputPrinter(new OutputColorizer());
-        $outputPrinter->warning(
+        $this->printDeprecationWarning(
             'The "withRealPathReporting()" method is deprecated. Use the JSON output format ("--output-format json") to get absolute paths.'
         );
         return $this;
     }
 
+    /**
+     * Skips parallel worker processes, so the main command prints each deprecation once.
+     */
+    private function printDeprecationWarning(string $message): void
+    {
+        if (($_SERVER['argv'][1] ?? null) === 'worker') {
+            return;
+        }
+
+        // config file is loaded twice per process (container build + cache hash), warn only once
+        static $printedMessages = [];
+        if (isset($printedMessages[$message])) {
+            return;
+        }
+
+        $printedMessages[$message] = true;
+
+        $outputPrinter = new OutputPrinter(new OutputColorizer());
+        $outputPrinter->warning($message);
+    }
+
     /**
      * Raise your spacing coverage from the safest rules
      * to more affecting ones, one level at a time.
diff --git a/tests/Configuration/DeprecatedPhpCsFixerSetsTest.php b/tests/Configuration/DeprecatedPhpCsFixerSetsTest.php
index 3628cc2c79..7fb7be61b7 100644
--- a/tests/Configuration/DeprecatedPhpCsFixerSetsTest.php
+++ b/tests/Configuration/DeprecatedPhpCsFixerSetsTest.php
@@ -19,4 +19,18 @@ public function testAcceptsLegacyNamedArgumentsWithoutCrashing(): void
 
         self::assertSame($ecsConfigBuilder, $result);
     }
+
+    public function testSkipsDeprecationWarningInParallelWorker(): void
+    {
+        $originalArgv = $_SERVER['argv'];
+        $_SERVER['argv'] = ['bin/ecs', 'worker', '--config', 'ecs.php'];
+
+        ob_start();
+        new ECSConfigBuilder()->withEditorConfig();
+        $output = ob_get_clean();
+
+        $_SERVER['argv'] = $originalArgv;
+
+        self::assertSame('', $output);
+    }
 }