diff --git a/core/src/main/scala/org/apache/spark/internal/config/package.scala b/core/src/main/scala/org/apache/spark/internal/config/package.scala
index 5edb24a6eb3e8..ff887181e1a2e 100644
--- a/core/src/main/scala/org/apache/spark/internal/config/package.scala
+++ b/core/src/main/scala/org/apache/spark/internal/config/package.scala
@@ -2946,7 +2946,8 @@ package object config {
   private[spark] val DRIVER_LIMIT_ACTIVE_PROCESSOR_COUNT_ENABLED =
     ConfigBuilder("spark.driver.limitActiveProcessorCount.enabled")
       .doc("Whether to add -XX:ActiveProcessorCount=<spark.driver.cores> to the driver JVM " +
-        "options. Currently, this only takes effect in YARN cluster mode.")
+        "options. In YARN cluster mode, the count is set to <spark.driver.cores>. " +
+        "In local mode, it is applied at submit time via SparkSubmit.")
       .version("4.2.0")
       .booleanConf
       .createWithDefault(false)
diff --git a/launcher/src/main/java/org/apache/spark/launcher/SparkSubmitCommandBuilder.java b/launcher/src/main/java/org/apache/spark/launcher/SparkSubmitCommandBuilder.java
index 73336b55b89d4..74669a84bfe59 100644
--- a/launcher/src/main/java/org/apache/spark/launcher/SparkSubmitCommandBuilder.java
+++ b/launcher/src/main/java/org/apache/spark/launcher/SparkSubmitCommandBuilder.java
@@ -339,6 +339,32 @@ private List<String> buildSparkSubmitCommand(Map<String, String> env)
     checkJavaOptions(driverExtraJavaOptions);
 
     if (isClientMode) {
+      if (isLocalMode(config)) {
+        String limitAPC = config.get("spark.driver.limitActiveProcessorCount.enabled");
+        if ("true".equalsIgnoreCase(limitAPC)) {
+          // Skip injection if the user already specified -XX:ActiveProcessorCount explicitly.
+          boolean alreadySet =
+            containsActiveProcessorCount(driverDefaultJavaOptions) ||
+            containsActiveProcessorCount(driverExtraJavaOptions);
+          if (!alreadySet) {
+            int cores = 1;
+            String driverCoresStr = config.get("spark.driver.cores");
+            if (driverCoresStr != null) {
+              try {
+                cores = Integer.parseInt(driverCoresStr.trim());
+              } catch (NumberFormatException e) {
+                throw new IllegalArgumentException(
+                  "Invalid value for spark.driver.cores: '" + driverCoresStr + "'", e);
+              }
+              if (cores < 1) {
+                throw new IllegalArgumentException(
+                  "spark.driver.cores must be >= 1, got: " + cores);
+              }
+            }
+            cmd.add("-XX:ActiveProcessorCount=" + cores);
+          }
+        }
+      }
       // Figuring out where the memory value come from is a little tricky due to precedence.
       // Precedence is observed in the following order:
       // - explicit configuration (setConf()), which also covers --driver-memory cli argument.
@@ -487,6 +513,23 @@ boolean isClientMode(Map<String, String> userProps) {
     return userMaster == null || userDeployMode == null || "client".equals(userDeployMode);
   }
 
+  private boolean isLocalMode(Map<String, String> userProps) {
+    String userMaster = firstNonEmpty(master, userProps.get(SparkLauncher.SPARK_MASTER));
+    // null master defaults to local[*] (see isClientMode comment above); match "local" and
+    // "local[N]"/"local[*]" but not "local-cluster[...]" which runs separate worker processes.
+    return userMaster == null ||
+      userMaster.trim().equals("local") ||
+      userMaster.trim().startsWith("local[");
+  }
+
+  private static boolean containsActiveProcessorCount(String javaOptions) {
+    if (isEmpty(javaOptions)) return false;
+    for (String opt : CommandBuilderUtils.parseOptionString(javaOptions)) {
+      if (opt.startsWith("-XX:ActiveProcessorCount=")) return true;
+    }
+    return false;
+  }
+
   /**
    * Return whether the given main class represents a thrift server.
    */
@@ -564,6 +607,7 @@ protected boolean handle(String opt, String value) {
         case EXTRA_PROPERTIES_FILE -> extraPropertiesFiles.add(value);
         case LOAD_SPARK_DEFAULTS -> loadSparkDefaults = true;
         case DRIVER_MEMORY -> conf.put(SparkLauncher.DRIVER_MEMORY, value);
+        case DRIVER_CORES -> conf.put("spark.driver.cores", value); // no SparkLauncher constant
         case DRIVER_JAVA_OPTIONS -> conf.put(SparkLauncher.DRIVER_EXTRA_JAVA_OPTIONS, value);
         case DRIVER_LIBRARY_PATH -> conf.put(SparkLauncher.DRIVER_EXTRA_LIBRARY_PATH, value);
         case DRIVER_DEFAULT_CLASS_PATH ->
diff --git a/launcher/src/test/java/org/apache/spark/launcher/SparkSubmitCommandBuilderSuite.java b/launcher/src/test/java/org/apache/spark/launcher/SparkSubmitCommandBuilderSuite.java
index d1dba85a534f2..366a17bc63d9b 100644
--- a/launcher/src/test/java/org/apache/spark/launcher/SparkSubmitCommandBuilderSuite.java
+++ b/launcher/src/test/java/org/apache/spark/launcher/SparkSubmitCommandBuilderSuite.java
@@ -388,6 +388,98 @@ public void testIsClientMode() {
     assertTrue(builder.isClientMode(userProps));
   }
 
+  @Test
+  public void testLimitActiveProcessorCountLocalMode() throws Exception {
+    // Flag disabled (default): no -XX:ActiveProcessorCount in command
+    List<String> cmd = buildCommand(
+        parser.MASTER, "local[4]",
+        SparkLauncher.NO_RESOURCE);
+    assertFalse(cmd.stream().anyMatch(a -> a.startsWith("-XX:ActiveProcessorCount")));
+
+    // Flag explicitly disabled: no -XX:ActiveProcessorCount in command
+    cmd = buildCommand(
+        parser.MASTER, "local[4]",
+        parser.CONF, "spark.driver.limitActiveProcessorCount.enabled=false",
+        SparkLauncher.NO_RESOURCE);
+    assertFalse(cmd.stream().anyMatch(a -> a.startsWith("-XX:ActiveProcessorCount")));
+
+    // Local mode (bare "local"), flag enabled, default cores (1)
+    cmd = buildCommand(
+        parser.MASTER, "local",
+        parser.CONF, "spark.driver.limitActiveProcessorCount.enabled=true",
+        SparkLauncher.NO_RESOURCE);
+    assertTrue(cmd.contains("-XX:ActiveProcessorCount=1"));
+
+    // Local mode, flag enabled, default cores (1)
+    cmd = buildCommand(
+        parser.MASTER, "local[4]",
+        parser.CONF, "spark.driver.limitActiveProcessorCount.enabled=true",
+        SparkLauncher.NO_RESOURCE);
+    assertTrue(cmd.contains("-XX:ActiveProcessorCount=1"));
+
+    // Local mode, flag enabled, custom cores via --conf spark.driver.cores=4
+    cmd = buildCommand(
+        parser.MASTER, "local[4]",
+        parser.CONF, "spark.driver.limitActiveProcessorCount.enabled=true",
+        parser.CONF, "spark.driver.cores=4",
+        SparkLauncher.NO_RESOURCE);
+    assertTrue(cmd.contains("-XX:ActiveProcessorCount=4"));
+
+    // Local mode, flag enabled, custom cores via --driver-cores
+    cmd = buildCommand(
+        parser.MASTER, "local[4]",
+        parser.CONF, "spark.driver.limitActiveProcessorCount.enabled=true",
+        parser.DRIVER_CORES, "3",
+        SparkLauncher.NO_RESOURCE);
+    assertTrue(cmd.contains("-XX:ActiveProcessorCount=3"));
+
+    // YARN client mode, flag enabled: no -XX:ActiveProcessorCount in command
+    cmd = buildCommand(
+        parser.MASTER, "yarn",
+        parser.CONF, "spark.driver.limitActiveProcessorCount.enabled=true",
+        SparkLauncher.NO_RESOURCE);
+    assertFalse(cmd.stream().anyMatch(a -> a.startsWith("-XX:ActiveProcessorCount")));
+
+    // local-cluster mode, flag enabled: no -XX:ActiveProcessorCount in command
+    cmd = buildCommand(
+        parser.MASTER, "local-cluster[2,1,1024]",
+        parser.CONF, "spark.driver.limitActiveProcessorCount.enabled=true",
+        SparkLauncher.NO_RESOURCE);
+    assertFalse(cmd.stream().anyMatch(a -> a.startsWith("-XX:ActiveProcessorCount")));
+
+    // User already set -XX:ActiveProcessorCount in extraJavaOptions: skip auto-injection
+    cmd = buildCommand(
+        parser.MASTER, "local[4]",
+        parser.CONF, "spark.driver.limitActiveProcessorCount.enabled=true",
+        parser.DRIVER_JAVA_OPTIONS, "-XX:ActiveProcessorCount=8",
+        SparkLauncher.NO_RESOURCE);
+    assertTrue(cmd.contains("-XX:ActiveProcessorCount=8"));
+    assertEquals(1, cmd.stream().filter(a -> a.startsWith("-XX:ActiveProcessorCount")).count());
+
+    // User already set -XX:ActiveProcessorCount in defaultJavaOptions: skip auto-injection
+    cmd = buildCommand(
+        parser.MASTER, "local[4]",
+        parser.CONF, "spark.driver.limitActiveProcessorCount.enabled=true",
+        parser.CONF, SparkLauncher.DRIVER_DEFAULT_JAVA_OPTIONS + "=-XX:ActiveProcessorCount=5",
+        SparkLauncher.NO_RESOURCE);
+    assertTrue(cmd.contains("-XX:ActiveProcessorCount=5"));
+    assertEquals(1, cmd.stream().filter(a -> a.startsWith("-XX:ActiveProcessorCount")).count());
+
+    // Invalid spark.driver.cores: should throw
+    assertThrows(IllegalArgumentException.class, () -> buildCommand(
+        parser.MASTER, "local[4]",
+        parser.CONF, "spark.driver.limitActiveProcessorCount.enabled=true",
+        parser.CONF, "spark.driver.cores=abc",
+        SparkLauncher.NO_RESOURCE));
+
+    // Zero cores: should throw
+    assertThrows(IllegalArgumentException.class, () -> buildCommand(
+        parser.MASTER, "local[4]",
+        parser.CONF, "spark.driver.limitActiveProcessorCount.enabled=true",
+        parser.CONF, "spark.driver.cores=0",
+        SparkLauncher.NO_RESOURCE));
+  }
+
   private void testCmdBuilder(boolean isDriver, File propertiesFile) throws Exception {
     final String DRIVER_DEFAULT_PARAM = "-Ddriver-default";
     final String DRIVER_EXTRA_PARAM = "-Ddriver-extra";
@@ -530,6 +622,10 @@ private List<String> buildCommand(List<String> args, Map<String, String> env) th
     return newCommandBuilder(args).buildCommand(env);
   }
 
+  private List<String> buildCommand(String... args) throws Exception {
+    return buildCommand(Arrays.asList(args), new HashMap<>());
+  }
+
   private void testCLIOpts(String appResource, String opt, List<String> params) throws Exception {
     List<String> args = new ArrayList<>();
     if (appResource != null) {
@@ -543,5 +639,4 @@ private void testCLIOpts(String appResource, String opt, List<String> params) th
     List<String> cmd = buildCommand(args, env);
     assertTrue(cmd.contains(opt), opt + " should be contained in the final cmd.");
   }
-
 }