diff --git a/CHANGELOG.md b/CHANGELOG.md
index 5743ebc7fe..5e1df03dfd 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -6,6 +6,12 @@
 > make sure you follow our [migration guide](https://docs.sentry.io/platforms/react-native/migration/) first.
 <!-- prettier-ignore-end -->
 
+## Unreleased
+
+### Fixes
+
+- Skip iOS source maps upload on `Debug` builds ([#6405](https://github.com/getsentry/sentry-react-native/pull/6405))
+
 ## 8.17.2
 
 ### Fixes
diff --git a/packages/core/scripts/sentry-xcode.sh b/packages/core/scripts/sentry-xcode.sh
index aa4ead6225..1a44688e99 100755
--- a/packages/core/scripts/sentry-xcode.sh
+++ b/packages/core/scripts/sentry-xcode.sh
@@ -65,7 +65,18 @@ REACT_NATIVE_XCODE_WITH_SENTRY="\"$SENTRY_CLI_EXECUTABLE\" react-native xcode $A
 
 exitCode=0
 
-if [ "$SENTRY_DISABLE_AUTO_UPLOAD" != true ]; then
+if [ "$SENTRY_DISABLE_AUTO_UPLOAD" == true ]; then
+  echo "SENTRY_DISABLE_AUTO_UPLOAD=true, skipping sourcemaps upload"
+  /bin/sh -c "$REACT_NATIVE_XCODE"
+elif echo "$CONFIGURATION" | grep -iq "debug"; then # case insensitive check for "debug"
+  # Skip the source maps upload for *Debug* configuration, matching the behavior of the
+  # native debug files upload (sentry-xcode-debug-files.sh) and the Android Gradle plugin.
+  # Local Debug builds should not require Sentry credentials. Still run the React Native
+  # bundling step so the build itself succeeds.
+  # See: https://github.com/getsentry/sentry-react-native/issues/6399
+  echo "Skipping source maps upload for *Debug* configuration"
+  /bin/sh -c "$REACT_NATIVE_XCODE"
+else
   # 'warning:' triggers a warning in Xcode, 'error:' triggers an error
   set +x +e # disable printing commands otherwise we might print `error:` by accident and allow continuing on error
   SENTRY_XCODE_COMMAND_OUTPUT=$(/bin/sh -c "\"$LOCAL_NODE_BINARY\" $REACT_NATIVE_XCODE_WITH_SENTRY" 2>&1)
@@ -82,9 +93,6 @@ if [ "$SENTRY_DISABLE_AUTO_UPLOAD" != true ]; then
     fi
   fi
   set -x -e # re-enable
-else
-  echo "SENTRY_DISABLE_AUTO_UPLOAD=true, skipping sourcemaps upload"
-  /bin/sh -c "$REACT_NATIVE_XCODE"
 fi
 
 [ -z "$SENTRY_COLLECT_MODULES" ] && SENTRY_RN_PACKAGE_PATH=$("$LOCAL_NODE_BINARY" --print "require('path').dirname(require.resolve('@sentry/react-native/package.json'))")
diff --git a/packages/core/test/scripts/sentry-xcode-scripts.test.ts b/packages/core/test/scripts/sentry-xcode-scripts.test.ts
index 90eedcd6c8..3a65af4cae 100644
--- a/packages/core/test/scripts/sentry-xcode-scripts.test.ts
+++ b/packages/core/test/scripts/sentry-xcode-scripts.test.ts
@@ -455,6 +455,32 @@ describe('sentry-xcode.sh', () => {
     expect(result.stdout).toContain('skipping sourcemaps upload');
   });
 
+  it('skips upload for Debug configuration without invoking sentry-cli', () => {
+    const result = runScript({
+      CONFIGURATION: 'Debug',
+      // A failing sentry-cli would surface here if it were invoked; the Debug skip must run
+      // the React Native bundling step directly instead. See issue #6399.
+      MOCK_CLI_EXIT_CODE: '1',
+      MOCK_CLI_OUTPUT: 'An organization ID or slug is required',
+    });
+
+    expect(result.exitCode).toBe(0);
+    expect(result.stdout).toContain('Skipping source maps upload for *Debug* configuration');
+    expect(result.stdout).toContain('Mock React Native bundle');
+    expect(result.stdout).not.toContain('An organization ID or slug is required');
+    expect(result.stdout).not.toContain('error: sentry-cli');
+  });
+
+  it('skips upload for debug configuration (case insensitive)', () => {
+    const result = runScript({
+      CONFIGURATION: 'debug',
+    });
+
+    expect(result.exitCode).toBe(0);
+    expect(result.stdout).toContain('Skipping source maps upload for *Debug* configuration');
+    expect(result.stdout).toContain('Mock React Native bundle');
+  });
+
   describe('SENTRY_PROJECT_ROOT override', () => {
     it('resolves SOURCEMAP_FILE relative to SENTRY_PROJECT_ROOT instead of PROJECT_DIR/..', () => {
       const customRoot = path.join(tempDir, 'monorepo-package');