diff --git a/docs/changes/README.md b/docs/changes/README.md
index 05092fb79..9fbe75076 100644
--- a/docs/changes/README.md
+++ b/docs/changes/README.md
@@ -3,6 +3,11 @@
 
 ## [Unreleased](https://github.com/GradleUp/shadow/compare/9.1.0...HEAD) - 2025-xx-xx
 
+### Changed
+
+- Merge Gradle Module descriptors into the modern `META-INF` path. ([#1706](https://github.com/GradleUp/shadow/pull/1706))  
+  The Gradle Module descriptors (`org.codehaus.groovy.runtime.ExtensionModule` files) defined under `META-INF/services/`
+  and `META-INF/groovy` will be merged into `META-INF/groovy/org.codehaus.groovy.runtime.ExtensionModule`.
 
 ## [9.1.0](https://github.com/GradleUp/shadow/compare/9.1.0) - 2025-08-29
 
diff --git a/src/functionalTest/kotlin/com/github/jengelman/gradle/plugins/shadow/transformers/GroovyExtensionModuleTransformerTest.kt b/src/functionalTest/kotlin/com/github/jengelman/gradle/plugins/shadow/transformers/GroovyExtensionModuleTransformerTest.kt
index 5ed589c12..898b8df69 100644
--- a/src/functionalTest/kotlin/com/github/jengelman/gradle/plugins/shadow/transformers/GroovyExtensionModuleTransformerTest.kt
+++ b/src/functionalTest/kotlin/com/github/jengelman/gradle/plugins/shadow/transformers/GroovyExtensionModuleTransformerTest.kt
@@ -13,8 +13,9 @@ import com.github.jengelman.gradle.plugins.shadow.transformers.GroovyExtensionMo
 import com.github.jengelman.gradle.plugins.shadow.util.getContent
 import java.nio.file.Path
 import kotlin.io.path.appendText
-import org.junit.jupiter.api.Test
 import org.junit.jupiter.params.ParameterizedTest
+import org.junit.jupiter.params.provider.Arguments
+import org.junit.jupiter.params.provider.MethodSource
 import org.junit.jupiter.params.provider.ValueSource
 
 class GroovyExtensionModuleTransformerTest : BaseTransformerTest() {
@@ -39,23 +40,27 @@ class GroovyExtensionModuleTransformerTest : BaseTransformerTest() {
 
     run(shadowJarPath)
 
-    commonAssertions(PATH_GROOVY_EXTENSION_MODULE_DESCRIPTOR)
+    commonAssertions()
   }
 
-  @Test
-  fun groovyExtensionModuleTransformerWorksForLegacyGroovy() {
+  @ParameterizedTest
+  @MethodSource("resourcePathProvider")
+  fun mergeLegacyAndModernModuleDescriptorsIntoTheNewResourcePath(
+    fooEntry: String,
+    barEntry: String,
+  ) {
     projectScript.appendText(
       transform<GroovyExtensionModuleTransformer>(
         dependenciesBlock = implementationFiles(
-          buildJarFoo(PATH_LEGACY_GROOVY_EXTENSION_MODULE_DESCRIPTOR),
-          buildJarBar(PATH_LEGACY_GROOVY_EXTENSION_MODULE_DESCRIPTOR),
+          buildJarFoo(fooEntry),
+          buildJarBar(barEntry),
         ),
       ),
     )
 
     run(shadowJarPath)
 
-    commonAssertions(PATH_LEGACY_GROOVY_EXTENSION_MODULE_DESCRIPTOR)
+    commonAssertions()
   }
 
   private fun buildJarFoo(
@@ -86,8 +91,8 @@ class GroovyExtensionModuleTransformerTest : BaseTransformerTest() {
     )
   }
 
-  private fun commonAssertions(entry: String) {
-    val properties = outputShadowedJar.use { it.getContent(entry) }.toProperties()
+  private fun commonAssertions() {
+    val properties = outputShadowedJar.use { it.getContent(PATH_GROOVY_EXTENSION_MODULE_DESCRIPTOR) }.toProperties()
 
     assertThat(properties.getProperty(KEY_MODULE_NAME)).isEqualTo(MERGED_MODULE_NAME)
     assertThat(properties.getProperty(KEY_MODULE_VERSION)).isEqualTo(MERGED_MODULE_VERSION)
@@ -102,5 +107,13 @@ class GroovyExtensionModuleTransformerTest : BaseTransformerTest() {
     const val EXTENSION_CLASSES_BAR = "com.acme.bar.SomeExtension,com.acme.bar.AnotherExtension"
     const val STATIC_EXTENSION_CLASSES_FOO = "com.acme.foo.FooStaticExtension"
     const val STATIC_EXTENSION_CLASSES_BAR = "com.acme.bar.SomeStaticExtension"
+
+    @JvmStatic
+    fun resourcePathProvider() = listOf(
+      Arguments.of(PATH_LEGACY_GROOVY_EXTENSION_MODULE_DESCRIPTOR, PATH_LEGACY_GROOVY_EXTENSION_MODULE_DESCRIPTOR),
+      Arguments.of(PATH_GROOVY_EXTENSION_MODULE_DESCRIPTOR, PATH_GROOVY_EXTENSION_MODULE_DESCRIPTOR),
+      Arguments.of(PATH_LEGACY_GROOVY_EXTENSION_MODULE_DESCRIPTOR, PATH_GROOVY_EXTENSION_MODULE_DESCRIPTOR),
+      Arguments.of(PATH_GROOVY_EXTENSION_MODULE_DESCRIPTOR, PATH_LEGACY_GROOVY_EXTENSION_MODULE_DESCRIPTOR),
+    )
   }
 }
diff --git a/src/main/kotlin/com/github/jengelman/gradle/plugins/shadow/transformers/GroovyExtensionModuleTransformer.kt b/src/main/kotlin/com/github/jengelman/gradle/plugins/shadow/transformers/GroovyExtensionModuleTransformer.kt
index 887e485fb..885dfcf67 100644
--- a/src/main/kotlin/com/github/jengelman/gradle/plugins/shadow/transformers/GroovyExtensionModuleTransformer.kt
+++ b/src/main/kotlin/com/github/jengelman/gradle/plugins/shadow/transformers/GroovyExtensionModuleTransformer.kt
@@ -21,26 +21,15 @@ import org.gradle.api.file.FileTreeElement
  * files came from the legacy location, otherwise it will be written into the now standard location (META-INF/groovy).
  * Note that certain JDK9+ tooling will break when using the legacy location.
  *
- * Modified from [eu.appsatori.gradle.fatjar.tasks.PrepareFiles.groovy](https://github.com/musketyr/gradle-fatjar-plugin/blob/master/src/main/groovy/eu/appsatori/gradle/fatjar/tasks/PrepareFiles.groovy).
  * Related to [org.apache.maven.plugins.shade.resource.GroovyResourceTransformer.java](https://github.com/apache/maven-shade-plugin/blob/master/src/main/java/org/apache/maven/plugins/shade/resource/GroovyResourceTransformer.java).
  */
 @CacheableTransformer
 public open class GroovyExtensionModuleTransformer : ResourceTransformer {
   private val module = Properties()
 
-  /**
-   * default to Groovy 2.4 or earlier
-   */
-  private var legacy = true
-
   override fun canTransformResource(element: FileTreeElement): Boolean {
     val path = element.path
-    if (path == PATH_GROOVY_EXTENSION_MODULE_DESCRIPTOR) {
-      // Groovy 2.5+
-      legacy = false
-      return true
-    }
-    return path == PATH_LEGACY_GROOVY_EXTENSION_MODULE_DESCRIPTOR
+    return path == PATH_LEGACY_GROOVY_EXTENSION_MODULE_DESCRIPTOR || path == PATH_GROOVY_EXTENSION_MODULE_DESCRIPTOR
   }
 
   override fun transform(context: TransformerContext) {
@@ -64,26 +53,28 @@ public open class GroovyExtensionModuleTransformer : ResourceTransformer {
     }
   }
 
-  private fun handle(key: String, value: String, mergeValue: (String) -> Unit) {
-    val existingValue = module.getProperty(key)
-    if (existingValue != null) {
-      mergeValue(existingValue)
-    } else {
-      module.setProperty(key, value)
-    }
-  }
-
   override fun hasTransformedResource(): Boolean = module.isNotEmpty()
 
   override fun modifyOutputStream(os: ZipOutputStream, preserveFileTimestamps: Boolean) {
-    val name = if (legacy) PATH_LEGACY_GROOVY_EXTENSION_MODULE_DESCRIPTOR else PATH_GROOVY_EXTENSION_MODULE_DESCRIPTOR
-    os.putNextEntry(zipEntry(name, preserveFileTimestamps))
+    os.putNextEntry(zipEntry(PATH_GROOVY_EXTENSION_MODULE_DESCRIPTOR, preserveFileTimestamps))
     module.inputStream().use {
       it.copyTo(os)
     }
     os.closeEntry()
   }
 
+  private fun handle(key: String, value: String, mergeValue: (String) -> Unit) {
+    val existingValue = module.getProperty(key)
+    if (existingValue != null) {
+      mergeValue(existingValue)
+    } else {
+      module.setProperty(key, value)
+    }
+  }
+
+  /*
+   * https://groovy-lang.org/metaprogramming.html#module-descriptor
+   */
   public companion object {
     public const val PATH_LEGACY_GROOVY_EXTENSION_MODULE_DESCRIPTOR: String =
       "META-INF/services/org.codehaus.groovy.runtime.ExtensionModule"