diff --git a/project-generator/src/main/kotlin/io/github/cdsap/projectgenerator/generator/plugins/android/CompositeBuildPluginAndroidApp.kt b/project-generator/src/main/kotlin/io/github/cdsap/projectgenerator/generator/plugins/android/CompositeBuildPluginAndroidApp.kt
index 3b686664..8188e75b 100644
--- a/project-generator/src/main/kotlin/io/github/cdsap/projectgenerator/generator/plugins/android/CompositeBuildPluginAndroidApp.kt
+++ b/project-generator/src/main/kotlin/io/github/cdsap/projectgenerator/generator/plugins/android/CompositeBuildPluginAndroidApp.kt
@@ -12,13 +12,13 @@ class CompositeBuildPluginAndroidApp {
         |import org.gradle.api.Plugin
         |import org.gradle.api.JavaVersion
         |import org.gradle.api.Project
+        |import org.gradle.api.plugins.JavaPluginExtension
         |import org.gradle.kotlin.dsl.configure
         |import org.gradle.api.tasks.compile.JavaCompile
         |import org.gradle.jvm.toolchain.JavaLanguageVersion
         |import org.gradle.jvm.toolchain.JavaToolchainService
         |import org.gradle.kotlin.dsl.dependencies
         |import org.gradle.kotlin.dsl.withType
-        |import org.jetbrains.kotlin.gradle.dsl.KotlinAndroidProjectExtension
         |
         |class CompositeBuildPluginAndroidApp : Plugin<Project> {
         |    override fun apply(target: Project) {
@@ -51,11 +51,12 @@ class CompositeBuildPluginAndroidApp {
         |                buildFeatures {
         |                    compose = true
         |                }
+        |                compileOptions {
+        |                    sourceCompatibility = JavaVersion.VERSION_${versions.project.jdk}
+        |                    targetCompatibility = JavaVersion.VERSION_${versions.project.jdk}
+        |                }
         |            }
-        |            target.extensions.getByType(KotlinAndroidProjectExtension::class.java).apply {
-        |                    jvmToolchain(${versions.project.jdk})
-        |            }
-        |            target.extensions.getByType(org.gradle.api.plugins.JavaPluginExtension::class.java).apply {
+        |            target.extensions.getByType(JavaPluginExtension::class.java).apply {
         |                toolchain.languageVersion.set(org.gradle.jvm.toolchain.JavaLanguageVersion.of(${versions.project.jdk}))
         |            }
         |            ${hiltToolchainFix(versions, di)}
@@ -70,7 +71,11 @@ class CompositeBuildPluginAndroidApp {
 
     fun provideKotlinProcessor(versions: Versions, di: DependencyInjection): String {
         if (versions.kotlin.kotlinProcessor.processor == Processor.KAPT) {
-            return """apply("kotlin-kapt")"""
+            return if (versions.android.agp.isAgp9()) {
+                """apply("com.android.legacy-kapt")"""
+            } else {
+                """apply("kotlin-kapt")"""
+            }
         }
         val shouldApplyKsp = di == DependencyInjection.HILT || versions.android.roomDatabase
         return if (shouldApplyKsp) """apply("com.google.devtools.ksp")""" else ""
diff --git a/project-generator/src/main/kotlin/io/github/cdsap/projectgenerator/generator/plugins/android/CompositeBuildPluginAndroidKmpLib.kt b/project-generator/src/main/kotlin/io/github/cdsap/projectgenerator/generator/plugins/android/CompositeBuildPluginAndroidKmpLib.kt
index 0708d2e6..3e275101 100644
--- a/project-generator/src/main/kotlin/io/github/cdsap/projectgenerator/generator/plugins/android/CompositeBuildPluginAndroidKmpLib.kt
+++ b/project-generator/src/main/kotlin/io/github/cdsap/projectgenerator/generator/plugins/android/CompositeBuildPluginAndroidKmpLib.kt
@@ -1,5 +1,6 @@
 package io.github.cdsap.projectgenerator.generator.plugins.android
 
+import io.github.cdsap.projectgenerator.generator.extension.isAgp9
 import io.github.cdsap.projectgenerator.model.DependencyInjection
 import io.github.cdsap.projectgenerator.model.Processor
 import io.github.cdsap.projectgenerator.model.Versions
@@ -56,7 +57,11 @@ class CompositeBuildPluginAndroidKmpLib {
 
     private fun provideKotlinProcessor(versions: Versions, di: DependencyInjection): String {
         if (versions.kotlin.kotlinProcessor.processor == Processor.KAPT) {
-            return """apply("kotlin-kapt")"""
+            return if (versions.android.agp.isAgp9()) {
+                """apply("com.android.legacy-kapt")"""
+            } else {
+                """apply("kotlin-kapt")"""
+            }
         }
         val shouldApplyKsp = di == DependencyInjection.HILT || versions.android.roomDatabase
         return if (shouldApplyKsp) """apply("com.google.devtools.ksp")""" else ""
diff --git a/project-generator/src/main/kotlin/io/github/cdsap/projectgenerator/generator/plugins/android/CompositeBuildPluginAndroidLib.kt b/project-generator/src/main/kotlin/io/github/cdsap/projectgenerator/generator/plugins/android/CompositeBuildPluginAndroidLib.kt
index c86db2c6..db97eb2a 100644
--- a/project-generator/src/main/kotlin/io/github/cdsap/projectgenerator/generator/plugins/android/CompositeBuildPluginAndroidLib.kt
+++ b/project-generator/src/main/kotlin/io/github/cdsap/projectgenerator/generator/plugins/android/CompositeBuildPluginAndroidLib.kt
@@ -12,9 +12,9 @@ class CompositeBuildPluginAndroidLib {
         |import org.gradle.api.Plugin
         |import org.gradle.api.JavaVersion
         |import org.gradle.api.Project
+        |import org.gradle.api.plugins.JavaPluginExtension
         |import org.gradle.kotlin.dsl.configure
         |import org.gradle.kotlin.dsl.dependencies
-        |import org.jetbrains.kotlin.gradle.dsl.KotlinAndroidProjectExtension
         |
         |class CompositeBuildPluginAndroidLib : Plugin<Project> {
         |    override fun apply(target: Project) {
@@ -49,11 +49,7 @@ class CompositeBuildPluginAndroidLib {
         |                }
         |            }
         |
-        |            target.extensions.getByType(KotlinAndroidProjectExtension::class.java).apply {
-        |                jvmToolchain(${versions.project.jdk})
-        |            }
-        |
-        |            target.extensions.getByType(org.gradle.api.plugins.JavaPluginExtension::class.java).apply {
+        |            target.extensions.getByType(JavaPluginExtension::class.java).apply {
         |                toolchain.languageVersion.set(org.gradle.jvm.toolchain.JavaLanguageVersion.of(${versions.project.jdk}))
         |            }
         |
@@ -67,7 +63,11 @@ class CompositeBuildPluginAndroidLib {
 
     fun provideKotlinProcessor(versions: Versions, di: DependencyInjection): String {
         if (versions.kotlin.kotlinProcessor.processor == Processor.KAPT) {
-            return """apply("kotlin-kapt")"""
+            return if (versions.android.agp.isAgp9()) {
+                """apply("com.android.legacy-kapt")"""
+            } else {
+                """apply("kotlin-kapt")"""
+            }
         }
         val shouldApplyKsp = di == DependencyInjection.HILT || versions.android.roomDatabase
         return if (shouldApplyKsp) """apply("com.google.devtools.ksp")""" else ""
diff --git a/project-generator/src/main/kotlin/io/github/cdsap/projectgenerator/generator/rootproject/BuildGradle.kt b/project-generator/src/main/kotlin/io/github/cdsap/projectgenerator/generator/rootproject/BuildGradle.kt
index 9a0d849d..da4120f2 100644
--- a/project-generator/src/main/kotlin/io/github/cdsap/projectgenerator/generator/rootproject/BuildGradle.kt
+++ b/project-generator/src/main/kotlin/io/github/cdsap/projectgenerator/generator/rootproject/BuildGradle.kt
@@ -1,5 +1,6 @@
 package io.github.cdsap.projectgenerator.generator.rootproject
 
+import io.github.cdsap.projectgenerator.generator.extension.isAgp9
 import io.github.cdsap.projectgenerator.model.DependencyInjection
 import io.github.cdsap.projectgenerator.model.Processor
 import io.github.cdsap.projectgenerator.model.Versions
@@ -9,7 +10,7 @@ class BuildGradle {
     fun getAndroid(versions: Versions, di: DependencyInjection) = """
         plugins {
             alias(libs.plugins.kotlin.jvm) apply false
-            alias(libs.plugins.kotlin.android) apply false
+            ${kotlinAndroidPlugin(versions)}
             alias(libs.plugins.kotlin.compose) apply false
             alias(libs.plugins.android.application) apply false
             ${androidLibraryRootPlugin(versions)}
@@ -56,4 +57,12 @@ class BuildGradle {
         }
     }
 
+    private fun kotlinAndroidPlugin(versions: Versions): String {
+        return if (versions.android.agp.isAgp9()) {
+            ""
+        } else {
+            "alias(libs.plugins.kotlin.android) apply false"
+        }
+    }
+
 }
diff --git a/project-generator/src/test/kotlin/io/github/cdsap/projectgenerator/AndroidKotlinMultiplatformLibraryE2EValidationTest.kt b/project-generator/src/test/kotlin/io/github/cdsap/projectgenerator/AndroidKotlinMultiplatformLibraryE2EValidationTest.kt
index 158b718d..973d4791 100644
--- a/project-generator/src/test/kotlin/io/github/cdsap/projectgenerator/AndroidKotlinMultiplatformLibraryE2EValidationTest.kt
+++ b/project-generator/src/test/kotlin/io/github/cdsap/projectgenerator/AndroidKotlinMultiplatformLibraryE2EValidationTest.kt
@@ -85,7 +85,7 @@ class AndroidKotlinMultiplatformLibraryE2EValidationTest {
     }
 
     private fun assemble(projectName: String) = GradleRunner.create()
-        .withProjectDir(File("$tempDir/$projectName/project_kts"))
+        .withProjectDir(File("$tempDir/$projectName/project_kts").also(AndroidSdkTestSupport::writeLocalProperties))
         .withArguments("assemble")
         .build()
 }
diff --git a/project-generator/src/test/kotlin/io/github/cdsap/projectgenerator/AndroidSdkTestSupport.kt b/project-generator/src/test/kotlin/io/github/cdsap/projectgenerator/AndroidSdkTestSupport.kt
new file mode 100644
index 00000000..627c8eaa
--- /dev/null
+++ b/project-generator/src/test/kotlin/io/github/cdsap/projectgenerator/AndroidSdkTestSupport.kt
@@ -0,0 +1,23 @@
+package io.github.cdsap.projectgenerator
+
+import org.junit.jupiter.api.Assumptions.assumeTrue
+import java.io.File
+
+object AndroidSdkTestSupport {
+    fun writeLocalProperties(projectDir: File) {
+        val sdkDir = androidSdkDir()
+        assumeTrue(sdkDir != null, "Android SDK not configured. Set ANDROID_HOME or ANDROID_SDK_ROOT.")
+
+        File(projectDir, "local.properties").writeText("sdk.dir=${sdkDir!!.invariantSeparatorsPath}\n")
+    }
+
+    private fun androidSdkDir(): File? {
+        return listOfNotNull(
+            System.getenv("ANDROID_HOME"),
+            System.getenv("ANDROID_SDK_ROOT"),
+            "${System.getProperty("user.home")}/Library/Android/sdk"
+        )
+            .map(::File)
+            .firstOrNull { it.isDirectory }
+    }
+}
diff --git a/project-generator/src/test/kotlin/io/github/cdsap/projectgenerator/RoomDiVariantsAssembleE2EValidationTest.kt b/project-generator/src/test/kotlin/io/github/cdsap/projectgenerator/RoomDiVariantsAssembleE2EValidationTest.kt
index 20622671..9a9b1576 100644
--- a/project-generator/src/test/kotlin/io/github/cdsap/projectgenerator/RoomDiVariantsAssembleE2EValidationTest.kt
+++ b/project-generator/src/test/kotlin/io/github/cdsap/projectgenerator/RoomDiVariantsAssembleE2EValidationTest.kt
@@ -49,6 +49,7 @@ class RoomDiVariantsAssembleE2EValidationTest {
         ).write()
 
         val projectDir = File("$tempDir/$projectName/project_kts")
+        AndroidSdkTestSupport.writeLocalProperties(projectDir)
         val assemble = GradleRunner.create()
             .withProjectDir(projectDir)
             .withArguments("clean", "assemble")
diff --git a/project-generator/src/test/kotlin/io/github/cdsap/projectgenerator/generator/rootproject/BuildGradleTest.kt b/project-generator/src/test/kotlin/io/github/cdsap/projectgenerator/generator/rootproject/BuildGradleTest.kt
new file mode 100644
index 00000000..73c9dcb3
--- /dev/null
+++ b/project-generator/src/test/kotlin/io/github/cdsap/projectgenerator/generator/rootproject/BuildGradleTest.kt
@@ -0,0 +1,35 @@
+package io.github.cdsap.projectgenerator.generator.rootproject
+
+import io.github.cdsap.projectgenerator.model.Android
+import io.github.cdsap.projectgenerator.model.Kotlin
+import io.github.cdsap.projectgenerator.model.KotlinProcessor
+import io.github.cdsap.projectgenerator.model.Processor
+import io.github.cdsap.projectgenerator.model.Versions
+import org.junit.jupiter.api.Assertions.assertFalse
+import org.junit.jupiter.api.Assertions.assertTrue
+import org.junit.jupiter.api.Test
+
+class BuildGradleTest {
+    @Test
+    fun `android root build file omits kotlin android plugin for agp9 built in kotlin`() {
+        val result = BuildGradle().getAndroid(Versions(), Versions().di)
+
+        assertFalse(result.contains("libs.plugins.kotlin.android"))
+    }
+
+    @Test
+    fun `android root build file keeps kotlin android plugin before agp9`() {
+        val result = BuildGradle().getAndroid(Versions(android = Android(agp = "8.13.0")), Versions().di)
+
+        assertTrue(result.contains("alias(libs.plugins.kotlin.android) apply false"))
+    }
+
+    @Test
+    fun `android root build file omits ksp plugin for kapt`() {
+        val versions = Versions(kotlin = Kotlin(kotlinProcessor = KotlinProcessor(Processor.KAPT)))
+
+        val result = BuildGradle().getAndroid(versions, versions.di)
+
+        assertFalse(result.contains("libs.plugins.kotlin.ksp"))
+    }
+}
diff --git a/project-generator/src/test/kotlin/io/github/cdsap/projectgenerator/writer/ConventionPluginWriterTest.kt b/project-generator/src/test/kotlin/io/github/cdsap/projectgenerator/writer/ConventionPluginWriterTest.kt
index 55a30eff..5c5a2f57 100644
--- a/project-generator/src/test/kotlin/io/github/cdsap/projectgenerator/writer/ConventionPluginWriterTest.kt
+++ b/project-generator/src/test/kotlin/io/github/cdsap/projectgenerator/writer/ConventionPluginWriterTest.kt
@@ -7,10 +7,14 @@ import io.github.cdsap.projectgenerator.generator.plugins.android.CompositeBuild
 import io.github.cdsap.projectgenerator.generator.plugins.android.CompositeBuildPluginAndroidLib
 import io.github.cdsap.projectgenerator.generator.plugins.jvm.CompositeBuildJvmLib
 import io.github.cdsap.projectgenerator.model.Android
+import io.github.cdsap.projectgenerator.model.Kotlin
+import io.github.cdsap.projectgenerator.model.KotlinProcessor
 import io.github.cdsap.projectgenerator.model.LanguageAttributes
+import io.github.cdsap.projectgenerator.model.Processor
 import io.github.cdsap.projectgenerator.model.TypeProjectRequested
 import io.github.cdsap.projectgenerator.model.Versions
 import org.junit.jupiter.api.Assertions.assertEquals
+import org.junit.jupiter.api.Assertions.assertFalse
 import org.junit.jupiter.api.Assertions.assertTrue
 import org.junit.jupiter.api.Test
 import org.junit.jupiter.api.io.TempDir
@@ -143,6 +147,28 @@ class ConventionPluginWriterTest {
         )
     }
 
+    @Test
+    fun `write should use legacy kapt plugin for agp9 built in kotlin`() {
+        val projectName = "androidKapt"
+        val language = LanguageAttributes(projectName = "${tempDir.path}/$projectName", extension = "gradle.kts")
+        val versions = Versions(kotlin = Kotlin(kotlinProcessor = KotlinProcessor(Processor.KAPT)))
+        val writer = ConventionPluginWriter(
+            languages = listOf(language),
+            versions = versions,
+            requested = TypeProjectRequested.ANDROID
+        )
+
+        writer.write()
+
+        val appPlugin = File("${language.projectName}/build-logic/convention/src/main/kotlin/com/logic/CompositeBuildPluginAndroidApp.kt")
+        val libPlugin = File("${language.projectName}/build-logic/convention/src/main/kotlin/com/logic/CompositeBuildPluginAndroidLib.kt")
+
+        assertTrue(appPlugin.readText().contains("apply(\"com.android.legacy-kapt\")"))
+        assertTrue(libPlugin.readText().contains("apply(\"com.android.legacy-kapt\")"))
+        assertFalse(appPlugin.readText().contains("apply(\"kotlin-kapt\")"))
+        assertFalse(libPlugin.readText().contains("apply(\"kotlin-kapt\")"))
+    }
+
     private fun assertAndroidConventionFilesExist(projectBasePath: String, versions: Versions) {
         val conventionSrcDir = File("$projectBasePath/build-logic/convention/src/main/kotlin/com/logic")
         assertTrue(conventionSrcDir.exists() && conventionSrcDir.isDirectory, "Convention src dir missing for $projectBasePath")