diff --git a/resource-managers/kubernetes/docker/src/main/dockerfiles/spark/entrypoint.sh b/resource-managers/kubernetes/docker/src/main/dockerfiles/spark/entrypoint.sh
index 42f4df88f3da9..3bed78292cbdd 100755
--- a/resource-managers/kubernetes/docker/src/main/dockerfiles/spark/entrypoint.sh
+++ b/resource-managers/kubernetes/docker/src/main/dockerfiles/spark/entrypoint.sh
@@ -30,12 +30,14 @@ set -e
 # If there is no passwd entry for the container UID, attempt to create one
 if [ -z "$uidentry" ] ; then
     if [ -w /etc/passwd ] ; then
-        echo "$myuid:x:$myuid:$mygid:${SPARK_USER_NAME:-anonymous uid}:$SPARK_HOME:/bin/false" >> /etc/passwd
+        echo "${SPARK_USER_NAME:-$myuid}:x:$myuid:$mygid:${SPARK_USER_NAME:-anonymous uid}:$SPARK_HOME:/bin/false" >> /etc/passwd
     else
         echo "Container ENTRYPOINT failed to add passwd entry for anonymous UID"
     fi
 fi
 
+echo "login user is `id -un`"
+
 if [ -z "$JAVA_HOME" ]; then
   JAVA_HOME=$(java -XshowSettings:properties -version 2>&1 > /dev/null | grep 'java.home' | awk '{print $3}')
 fi
diff --git a/resource-managers/kubernetes/integration-tests/src/test/scala/org/apache/spark/deploy/k8s/integrationtest/BasicTestsSuite.scala b/resource-managers/kubernetes/integration-tests/src/test/scala/org/apache/spark/deploy/k8s/integrationtest/BasicTestsSuite.scala
index af74032694db5..f7de43a53652b 100644
--- a/resource-managers/kubernetes/integration-tests/src/test/scala/org/apache/spark/deploy/k8s/integrationtest/BasicTestsSuite.scala
+++ b/resource-managers/kubernetes/integration-tests/src/test/scala/org/apache/spark/deploy/k8s/integrationtest/BasicTestsSuite.scala
@@ -24,7 +24,7 @@ import org.scalatest.matchers.should.Matchers._
 import org.scalatest.time.{Seconds, Span}
 
 import org.apache.spark.{SparkFunSuite, TestUtils}
-import org.apache.spark.deploy.k8s.integrationtest.KubernetesSuite.SPARK_PI_MAIN_CLASS
+import org.apache.spark.deploy.k8s.integrationtest.KubernetesSuite.{usernameTestTag, SPARK_PI_MAIN_CLASS}
 import org.apache.spark.launcher.SparkLauncher
 
 private[spark] trait BasicTestsSuite { k8sSuite: KubernetesSuite =>
@@ -168,6 +168,22 @@ private[spark] trait BasicTestsSuite { k8sSuite: KubernetesSuite =>
           .exists(envVar => envVar.getName == "SPARK_DRIVER_POD_IP")
       })
   }
+
+  test("SPARK-43171: Support custom Unix username in Pod", k8sTestTag, usernameTestTag) {
+    sparkAppConf
+      .set("spark.kubernetes.driverEnv.SPARK_USER_NAME", "spark-kube")
+      .set("spark.executorEnv.SPARK_USER_NAME", "spark-kube")
+    runSparkApplicationAndVerifyCompletion(
+      containerLocalSparkDistroExamplesJar,
+      SPARK_PI_MAIN_CLASS,
+      Seq("login user is spark-kube", "Pi is roughly 3"),
+      Seq("login user is spark-kube"),
+      appArgs = Array.empty,
+      doBasicDriverPodCheck,
+      doBasicExecutorPodCheck,
+      isJVM = true
+    )
+  }
 }
 
 private[spark] object BasicTestsSuite extends SparkFunSuite {
diff --git a/resource-managers/kubernetes/integration-tests/src/test/scala/org/apache/spark/deploy/k8s/integrationtest/KubernetesSuite.scala b/resource-managers/kubernetes/integration-tests/src/test/scala/org/apache/spark/deploy/k8s/integrationtest/KubernetesSuite.scala
index 78839ee610336..4b8ba23edd980 100644
--- a/resource-managers/kubernetes/integration-tests/src/test/scala/org/apache/spark/deploy/k8s/integrationtest/KubernetesSuite.scala
+++ b/resource-managers/kubernetes/integration-tests/src/test/scala/org/apache/spark/deploy/k8s/integrationtest/KubernetesSuite.scala
@@ -623,6 +623,7 @@ private[spark] object KubernetesSuite {
   val decomTestTag = Tag("decom")
   val rTestTag = Tag("r")
   val MinikubeTag = Tag("minikube")
+  val usernameTestTag = Tag("username")
   val SPARK_PI_MAIN_CLASS: String = "org.apache.spark.examples.SparkPi"
   val SPARK_DFS_READ_WRITE_TEST = "org.apache.spark.examples.DFSReadWriteTest"
   val SPARK_MINI_READ_WRITE_TEST = "org.apache.spark.examples.MiniReadWriteTest"