diff --git a/.github/workflows/build-and-test.yml b/.github/workflows/build-and-test.yml
index f429d0c1..1483bd02 100644
--- a/.github/workflows/build-and-test.yml
+++ b/.github/workflows/build-and-test.yml
@@ -18,7 +18,7 @@ jobs:
   build-test-linux:
     strategy:
       matrix:
-        java: [11, 17]
+        java: [21]
 
     name: Build CCR Plugin on Linux using Container Image
     runs-on: ubuntu-latest
diff --git a/.github/workflows/build.yml b/.github/workflows/build.yml
index 95e0b220..c77a52f1 100644
--- a/.github/workflows/build.yml
+++ b/.github/workflows/build.yml
@@ -16,7 +16,7 @@ jobs:
     strategy:
       matrix:
         java:
-          - 17
+          - 21
         os:
           - windows-latest
           - macos-latest
diff --git a/.github/workflows/bwc.yml b/.github/workflows/bwc.yml
index 4cce518e..85d9ade7 100644
--- a/.github/workflows/bwc.yml
+++ b/.github/workflows/bwc.yml
@@ -15,10 +15,10 @@ jobs:
     runs-on: ubuntu-latest
     steps:
       # This step uses the setup-java Github action: https://github.com/actions/setup-java
-      - name: Set Up JDK 11
+      - name: Set Up JDK 21
         uses: actions/setup-java@v1
         with:
-          java-version: 11
+          java-version: 21
       # This step uses the checkout Github action: https://github.com/actions/checkout
       - name: Checkout Branch
         uses: actions/checkout@v4
diff --git a/README.md b/README.md
index b2c537ef..c6a9afb0 100644
--- a/README.md
+++ b/README.md
@@ -45,7 +45,7 @@ The replication machinery is implemented as an OpenSearch plugin that exposes AP
 The project in this package uses the [Gradle](https://docs.gradle.org/current/userguide/userguide.html) build system. Gradle comes with excellent documentation that should be your first stop when trying to figure out how to operate or modify the build.
 
 ### Building from the command line
-Set JAVA_HOME to JDK-11 or above  
+Set JAVA_HOME to JDK-21 or above  
 
 1. `./gradlew build` builds and tests project.
 2. `./gradlew clean release` cleans previous builds, creates new build and tests project.
diff --git a/build.gradle b/build.gradle
index 94802834..715d432d 100644
--- a/build.gradle
+++ b/build.gradle
@@ -53,7 +53,7 @@ buildscript {
         plugin_previous_version = opensearch_previous_version.replaceAll(/(\.\d)([^\d]*)$/, '$1.0$2')
 
         common_utils_version = System.getProperty("common_utils.version", opensearch_build)
-        kotlin_version = System.getProperty("kotlin.version", "1.8.21")
+        kotlin_version = System.getProperty("kotlin.version", "1.9.25")
 
         security_plugin_version = opensearch_build
         if (!isSnapshot) {
@@ -89,6 +89,10 @@ plugins {
 allprojects {
     group = "org.opensearch"
     version = "${opensearch_build}"
+    plugins.withId('org.jetbrains.kotlin.jvm') {
+        compileJava.sourceCompatibility = compileJava.targetCompatibility = JavaVersion.VERSION_21
+        compileTestJava.sourceCompatibility = compileTestJava.targetCompatibility = JavaVersion.VERSION_21
+    }
 }
 
 apply plugin: 'java'
@@ -165,14 +169,14 @@ repositories {
 
 compileKotlin {
     kotlinOptions {
-        jvmTarget = "11"
+        jvmTarget = "21"
         freeCompilerArgs = ['-Xjsr305=strict'] // Handle OpenSearch @Nullable annotation correctly
     }
 }
 
 compileTestKotlin {
     kotlinOptions {
-        jvmTarget = "11"
+        jvmTarget = "21"
         freeCompilerArgs = ['-Xjsr305=strict']
     }
 }