diff --git a/launcher/src/main/java/org/apache/spark/launcher/AbstractCommandBuilder.java b/launcher/src/main/java/org/apache/spark/launcher/AbstractCommandBuilder.java
index d4d3faf83e3b0..caa2d2b5854e1 100644
--- a/launcher/src/main/java/org/apache/spark/launcher/AbstractCommandBuilder.java
+++ b/launcher/src/main/java/org/apache/spark/launcher/AbstractCommandBuilder.java
@@ -49,6 +49,7 @@ abstract class AbstractCommandBuilder {
   String master;
   String remote;
   protected String propertiesFile;
+  protected boolean loadSparkDefaults;
   final List<String> appArgs;
   final List<String> jars;
   final List<String> files;
@@ -362,21 +363,35 @@ Map<String, String> getEffectiveConfig() throws IOException {
   }
 
   /**
-   * Loads the configuration file for the application, if it exists. This is either the
-   * user-specified properties file, or the spark-defaults.conf file under the Spark configuration
-   * directory.
+   * Load the configuration file(s) for the application - from the user-specified properties
+   * file, and/or the spark-defaults.conf file under the Spark configuration directory, if exists.
+   * Configurations from user-specified properties file take precedence over spark-defaults.conf.
    */
   private Properties loadPropertiesFile() throws IOException {
     Properties props = new Properties();
-    File propsFile;
     if (propertiesFile != null) {
-      propsFile = new File(propertiesFile);
+      File propsFile = new File(propertiesFile);
       checkArgument(propsFile.isFile(), "Invalid properties file '%s'.", propertiesFile);
-    } else {
-      propsFile = new File(getConfDir(), DEFAULT_PROPERTIES_FILE);
+      props = loadPropertiesFile(propsFile);
     }
 
-    if (propsFile.isFile()) {
+    Properties defaultsProps = new Properties();
+    if (propertiesFile == null || loadSparkDefaults) {
+      defaultsProps = loadPropertiesFile(new File(getConfDir(), DEFAULT_PROPERTIES_FILE));
+    }
+
+    for (Map.Entry<Object, Object> entry : defaultsProps.entrySet()) {
+      if (!props.containsKey(entry.getKey())) {
+        props.put(entry.getKey(), entry.getValue());
+      }
+    }
+
+    return props;
+  }
+
+  private Properties loadPropertiesFile(File propsFile) throws IOException {
+    Properties props = new Properties();
+    if (propsFile != null && propsFile.isFile()) {
       try (InputStreamReader isr = new InputStreamReader(
           new FileInputStream(propsFile), StandardCharsets.UTF_8)) {
         props.load(isr);
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 bdbb954dbe087..7b9f90ac7b7a6 100644
--- a/launcher/src/main/java/org/apache/spark/launcher/SparkSubmitCommandBuilder.java
+++ b/launcher/src/main/java/org/apache/spark/launcher/SparkSubmitCommandBuilder.java
@@ -251,6 +251,10 @@ List<String> buildSparkSubmitArgs(boolean includeRemote) {
       args.add(propertiesFile);
     }
 
+    if (loadSparkDefaults) {
+      args.add(parser.LOAD_SPARK_DEFAULTS);
+    }
+
     if (isExample) {
       jars.addAll(findExamplesJars());
     }
@@ -550,6 +554,7 @@ protected boolean handle(String opt, String value) {
         }
         case DEPLOY_MODE -> deployMode = value;
         case PROPERTIES_FILE -> propertiesFile = value;
+        case LOAD_SPARK_DEFAULTS -> loadSparkDefaults = true;
         case DRIVER_MEMORY -> conf.put(SparkLauncher.DRIVER_MEMORY, value);
         case DRIVER_JAVA_OPTIONS -> conf.put(SparkLauncher.DRIVER_EXTRA_JAVA_OPTIONS, value);
         case DRIVER_LIBRARY_PATH -> conf.put(SparkLauncher.DRIVER_EXTRA_LIBRARY_PATH, value);
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 f0a295fb4228e..d1dba85a534f2 100644
--- a/launcher/src/test/java/org/apache/spark/launcher/SparkSubmitCommandBuilderSuite.java
+++ b/launcher/src/test/java/org/apache/spark/launcher/SparkSubmitCommandBuilderSuite.java
@@ -38,6 +38,7 @@ public class SparkSubmitCommandBuilderSuite extends BaseSuite {
 
   private static File dummyPropsFile;
   private static File connectPropsFile;
+  private static File driverMemPropsFile;
   private static SparkSubmitOptionParser parser;
 
   @BeforeAll
@@ -45,6 +46,9 @@ public static void setUp() throws Exception {
     dummyPropsFile = File.createTempFile("spark", "properties");
     connectPropsFile = File.createTempFile("spark", "properties");
     Files.writeString(connectPropsFile.toPath(), "spark.remote=sc://connect-server:15002");
+    driverMemPropsFile = File.createTempFile("spark", "properties");
+    Files.writeString(driverMemPropsFile.toPath(),
+        "spark.driver.memory=4g\nspark.driver.memoryOverhead=768m");
     parser = new SparkSubmitOptionParser();
   }
 
@@ -52,6 +56,73 @@ public static void setUp() throws Exception {
   public static void cleanUp() throws Exception {
     dummyPropsFile.delete();
     connectPropsFile.delete();
+    driverMemPropsFile.delete();
+  }
+
+  @Test
+  public void testGetEffectiveConfig() throws Exception {
+    doTestGetEffectiveConfig(null, true, true);
+    doTestGetEffectiveConfig(null, true, false);
+    doTestGetEffectiveConfig(null, false, true);
+    doTestGetEffectiveConfig(null, false, false);
+    doTestGetEffectiveConfig(driverMemPropsFile, true, true);
+    doTestGetEffectiveConfig(driverMemPropsFile, true, false);
+    doTestGetEffectiveConfig(driverMemPropsFile, false, true);
+    doTestGetEffectiveConfig(driverMemPropsFile, false, false);
+  }
+
+  private void doTestGetEffectiveConfig(
+      File propertiesFile, boolean loadSparkDefaults, boolean confDriverMemory) throws Exception {
+    SparkSubmitCommandBuilder launcher =
+        newCommandBuilder(Collections.emptyList());
+    launcher.loadSparkDefaults = loadSparkDefaults;
+    launcher.conf.put("spark.foo", "bar");
+    launcher.childEnv.put("SPARK_CONF_DIR", System.getProperty("spark.test.home")
+        + "/launcher/src/test/resources");
+
+    if (propertiesFile != null) {
+      launcher.setPropertiesFile(propertiesFile.getAbsolutePath());
+    }
+
+    if (confDriverMemory) {
+      launcher.conf.put(SparkLauncher.DRIVER_MEMORY, "2g");
+    }
+
+    Map<String, String> effectiveConfig = launcher.getEffectiveConfig();
+
+    assertEquals("bar", effectiveConfig.get("spark.foo"));
+    if (confDriverMemory) {
+      assertEquals("2g", effectiveConfig.get(SparkLauncher.DRIVER_MEMORY));
+    } else if (propertiesFile != null) {
+      try (FileReader reader = new FileReader(propertiesFile, StandardCharsets.UTF_8)) {
+        Properties props = new Properties();
+        props.load(reader);
+        if (props.containsKey(SparkLauncher.DRIVER_MEMORY)) {
+          assertEquals(props.getProperty(SparkLauncher.DRIVER_MEMORY),
+            effectiveConfig.get(SparkLauncher.DRIVER_MEMORY));
+        }
+      }
+    } else {
+      assertEquals("1g", effectiveConfig.get(SparkLauncher.DRIVER_MEMORY));
+    }
+
+    if (propertiesFile != null) {
+      try (FileReader reader = new FileReader(propertiesFile, StandardCharsets.UTF_8)) {
+        Properties props = new Properties();
+        props.load(reader);
+        if (props.containsKey("spark.driver.memoryOverhead")) {
+          assertEquals(props.getProperty("spark.driver.memoryOverhead"),
+              effectiveConfig.get("spark.driver.memoryOverhead"));
+        }
+      }
+      if (loadSparkDefaults) {
+        assertEquals("/driver", effectiveConfig.get(SparkLauncher.DRIVER_EXTRA_CLASSPATH));
+      } else {
+        assertFalse(effectiveConfig.containsKey(SparkLauncher.DRIVER_EXTRA_CLASSPATH));
+      }
+    } else {
+      assertEquals("/driver", effectiveConfig.get(SparkLauncher.DRIVER_EXTRA_CLASSPATH));
+    }
   }
 
   @Test