diff --git a/RELEASENOTES.md b/RELEASENOTES.md
index e4f845c04e..3fec448ca5 100644
--- a/RELEASENOTES.md
+++ b/RELEASENOTES.md
@@ -109,6 +109,9 @@
     *   Fix session description (SDP) parsing to use a HashMap-like behaviour
         for duplicated attributes.
         ([#9014](https://github.com/google/ExoPlayer/issues/9014)).
+*   OkHttp extension:
+    *   Switch to OkHttp 4.9.1. This increases the extension's minimum SDK
+        version requirement from 16 to 21.
 
 ### 2.14.1 (2021-06-11)
 
diff --git a/extensions/okhttp/build.gradle b/extensions/okhttp/build.gradle
index 758eb646f6..7589633208 100644
--- a/extensions/okhttp/build.gradle
+++ b/extensions/okhttp/build.gradle
@@ -13,6 +13,8 @@
 // limitations under the License.
 apply from: "$gradle.ext.exoplayerSettingsDir/common_library_config.gradle"
 
+android.defaultConfig.minSdkVersion 21
+
 dependencies {
     implementation project(modulePrefix + 'library-common')
     implementation 'androidx.annotation:annotation:' + androidxAnnotationVersion
@@ -21,11 +23,7 @@ dependencies {
     testImplementation project(modulePrefix + 'testutils')
     testImplementation 'com.squareup.okhttp3:mockwebserver:' + mockWebServerVersion
     testImplementation 'org.robolectric:robolectric:' + robolectricVersion
-    // Do not update to 3.13.X or later until minSdkVersion is increased to 21:
-    // https://cashapp.github.io/2019-02-05/okhttp-3-13-requires-android-5
-    // Since OkHttp is distributed as a jar rather than an aar, Gradle won't
-    // stop us from making this mistake!
-    api 'com.squareup.okhttp3:okhttp:3.12.11'
+    api 'com.squareup.okhttp3:okhttp:4.9.1'
 }
 
 ext {