diff --git a/.github/workflows/pipeline.yml b/.github/workflows/pipeline.yml
index a57dd29..3d559d7 100644
--- a/.github/workflows/pipeline.yml
+++ b/.github/workflows/pipeline.yml
@@ -34,7 +34,7 @@ jobs:
       - name: Set up JDK
         uses: actions/setup-java@v4
         with:
-          java-version: "17.0"
+          java-version: "21.0"
           distribution: "temurin"
       - name: Setup Gradle
         uses: gradle/actions/setup-gradle@db19848a5fa7950289d3668fb053140cf3028d43 # v3.3.0
@@ -54,7 +54,7 @@ jobs:
       - name: Set up JDK
         uses: actions/setup-java@v4
         with:
-          java-version: "17.0"
+          java-version: "21.0"
           distribution: "temurin"
       - name: Setup Gradle
         uses: gradle/actions/setup-gradle@db19848a5fa7950289d3668fb053140cf3028d43 # v3.3.0
@@ -77,7 +77,7 @@ jobs:
       - name: Set up JDK
         uses: actions/setup-java@v4
         with:
-          java-version: "17.0"
+          java-version: "21.0"
           distribution: "temurin"
       - name: Setup Gradle
         uses: gradle/actions/setup-gradle@db19848a5fa7950289d3668fb053140cf3028d43 # v3.3.0
@@ -127,7 +127,7 @@ jobs:
       - name: Set up JDK
         uses: actions/setup-java@v4
         with:
-          java-version: "17.0"
+          java-version: "21.0"
           distribution: "temurin"
       - name: Cache SonarQube packages
         uses: actions/cache@v4
@@ -175,7 +175,7 @@ jobs:
       - name: Set up JDK
         uses: actions/setup-java@v4
         with:
-          java-version: "17.0"
+          java-version: "21.0"
           distribution: "temurin"
       - name: Setup Gradle
         uses: gradle/actions/setup-gradle@db19848a5fa7950289d3668fb053140cf3028d43 # v3.3.0
diff --git a/README.md b/README.md
index a2ffc4d..d34966a 100644
--- a/README.md
+++ b/README.md
@@ -8,10 +8,10 @@ Kotlin service built with the [Spring WebFlux reactive stack](https://docs.sprin
 
 ## Prerequisites
 
-Kotlin 1.9 w/ Java 17, Docker for building + running the containerized application:
+Kotlin 1.9 w/ Java 21, Docker for building + running the containerized application:
 
 ```bash
-brew install openjdk@17
+brew install openjdk@21
 brew install --cask docker # or just `brew install docker` if you don't want the Desktop app
 ```
 
diff --git a/build.gradle.kts b/build.gradle.kts
index 68efb39..b100dac 100644
--- a/build.gradle.kts
+++ b/build.gradle.kts
@@ -18,7 +18,7 @@ plugins {
 
 group = "de.bund.digitalservice"
 version = "0.0.1-SNAPSHOT"
-java.sourceCompatibility = JavaVersion.VERSION_17
+java.sourceCompatibility = JavaVersion.VERSION_21
 
 repositories {
     mavenCentral()
@@ -98,7 +98,7 @@ tasks {
     withType<KotlinCompile> {
         kotlinOptions {
             freeCompilerArgs = listOf("-Xjsr305=strict")
-            jvmTarget = "17"
+            jvmTarget = "21"
         }
     }