diff --git a/CHANGELOG.md b/CHANGELOG.md
index 6418b28f9a..afe8eb0c41 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -8,6 +8,10 @@
 
 ## Unreleased
 
+### Fixes
+
+- Add `SENTRY_PROJECT_ROOT` env var to override project root in Xcode build phase scripts for monorepo setups ([#5961](https://github.com/getsentry/sentry-react-native/pull/5961))
+
 ### Features
 
 - Enable "Open Sentry" button in Playground for Expo apps ([#5947](https://github.com/getsentry/sentry-react-native/pull/5947))
diff --git a/packages/core/scripts/sentry-xcode-debug-files.sh b/packages/core/scripts/sentry-xcode-debug-files.sh
index e261b12c04..8bbd18a6f7 100755
--- a/packages/core/scripts/sentry-xcode-debug-files.sh
+++ b/packages/core/scripts/sentry-xcode-debug-files.sh
@@ -21,7 +21,10 @@ set -e
 LOCAL_NODE_BINARY=${NODE_BINARY:-node}
 
 # The project root by default is one level up from the ios directory
-RN_PROJECT_ROOT="${PROJECT_DIR}/.."
+# SENTRY_PROJECT_ROOT can be set to override this for monorepo setups
+# where the ios directory is not directly under the project root.
+# See: https://github.com/getsentry/sentry-react-native/issues/2880
+RN_PROJECT_ROOT="${SENTRY_PROJECT_ROOT:-${PROJECT_DIR}/..}"
 
 [ -z "$SENTRY_PROPERTIES" ] && export SENTRY_PROPERTIES=sentry.properties
 [ -z "$SENTRY_DOTENV_PATH" ] && [ -f "$RN_PROJECT_ROOT/.env.sentry-build-plugin" ] && export SENTRY_DOTENV_PATH="$RN_PROJECT_ROOT/.env.sentry-build-plugin"
diff --git a/packages/core/scripts/sentry-xcode.sh b/packages/core/scripts/sentry-xcode.sh
index 069f08be01..e8b52e846a 100755
--- a/packages/core/scripts/sentry-xcode.sh
+++ b/packages/core/scripts/sentry-xcode.sh
@@ -10,7 +10,10 @@ set -x -e
 LOCAL_NODE_BINARY=${NODE_BINARY:-node}
 
 # The project root by default is one level up from the ios directory
-RN_PROJECT_ROOT="${PROJECT_DIR}/.."
+# SENTRY_PROJECT_ROOT can be set to override this for monorepo setups
+# where the ios directory is not directly under the project root.
+# See: https://github.com/getsentry/sentry-react-native/issues/2880
+RN_PROJECT_ROOT="${SENTRY_PROJECT_ROOT:-${PROJECT_DIR}/..}"
 
 [ -z "$SENTRY_PROPERTIES" ] && export SENTRY_PROPERTIES=sentry.properties
 [ -z "$SENTRY_DOTENV_PATH" ] && [ -f "$RN_PROJECT_ROOT/.env.sentry-build-plugin" ] && export SENTRY_DOTENV_PATH="$RN_PROJECT_ROOT/.env.sentry-build-plugin"
diff --git a/packages/core/test/scripts/sentry-xcode-scripts.test.ts b/packages/core/test/scripts/sentry-xcode-scripts.test.ts
index ec0056fe7b..1f822db47e 100644
--- a/packages/core/test/scripts/sentry-xcode-scripts.test.ts
+++ b/packages/core/test/scripts/sentry-xcode-scripts.test.ts
@@ -455,6 +455,82 @@ describe('sentry-xcode.sh', () => {
     expect(result.stdout).toContain('skipping sourcemaps upload');
   });
 
+  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');
+      fs.mkdirSync(customRoot, { recursive: true });
+
+      const echoScript = path.join(tempDir, 'mock-sentry-cli-echo-sourcemap.js');
+      fs.writeFileSync(
+        echoScript,
+        `
+        const sourcemapFile = process.env.SOURCEMAP_FILE || 'not-set';
+        console.log('SOURCEMAP_FILE=' + sourcemapFile);
+        process.exit(0);
+        `,
+      );
+
+      const result = runScript({
+        SENTRY_PROJECT_ROOT: customRoot,
+        SENTRY_CLI_EXECUTABLE: echoScript,
+        SOURCEMAP_FILE: 'relative/path.map',
+      });
+
+      const expectedPath = path.join(customRoot, 'relative/path.map');
+      expect(result.exitCode).toBe(0);
+      expect(result.stdout).toContain(`SOURCEMAP_FILE=${expectedPath}`);
+    });
+
+    it('resolves SOURCEMAP_FILE relative to PROJECT_DIR/.. when SENTRY_PROJECT_ROOT is not set', () => {
+      const echoScript = path.join(tempDir, 'mock-sentry-cli-echo-sourcemap.js');
+      fs.writeFileSync(
+        echoScript,
+        `
+        const sourcemapFile = process.env.SOURCEMAP_FILE || 'not-set';
+        console.log('SOURCEMAP_FILE=' + sourcemapFile);
+        process.exit(0);
+        `,
+      );
+
+      const result = runScript({
+        SENTRY_CLI_EXECUTABLE: echoScript,
+        SOURCEMAP_FILE: 'relative/path.map',
+      });
+
+      // Without SENTRY_PROJECT_ROOT, falls back to PROJECT_DIR/..
+      const projectRoot = path.dirname(tempDir);
+      const expectedPath = path.join(projectRoot, 'relative/path.map');
+      expect(result.exitCode).toBe(0);
+      expect(result.stdout).toContain(`SOURCEMAP_FILE=${expectedPath}`);
+    });
+
+    it('finds sentry.options.json in SENTRY_PROJECT_ROOT', () => {
+      const customRoot = path.join(tempDir, 'monorepo-package');
+      fs.mkdirSync(customRoot, { recursive: true });
+
+      const optionsContent = JSON.stringify({ dsn: 'https://key@sentry.io/123' });
+      fs.writeFileSync(path.join(customRoot, 'sentry.options.json'), optionsContent);
+
+      const buildDir = path.join(tempDir, 'build');
+      const resourcesPath = 'Resources';
+      fs.mkdirSync(path.join(buildDir, resourcesPath), { recursive: true });
+
+      const result = runScript({
+        SENTRY_PROJECT_ROOT: customRoot,
+        SENTRY_DISABLE_AUTO_UPLOAD: 'true',
+        SENTRY_COPY_OPTIONS_FILE: 'true',
+        CONFIGURATION_BUILD_DIR: buildDir,
+        UNLOCALIZED_RESOURCES_FOLDER_PATH: resourcesPath,
+      });
+
+      expect(result.exitCode).toBe(0);
+      expect(result.stdout).toContain('Copied');
+      const destPath = path.join(buildDir, resourcesPath, 'sentry.options.json');
+      const copied = JSON.parse(fs.readFileSync(destPath, 'utf8'));
+      expect(copied.dsn).toBe('https://key@sentry.io/123');
+    });
+  });
+
   describe('sentry.options.json SENTRY_ENVIRONMENT override', () => {
     it('copies file without modification when SENTRY_ENVIRONMENT is not set', () => {
       const optionsContent = JSON.stringify({ dsn: 'https://key@sentry.io/123', environment: 'production' });