diff --git a/apps/oxlint/src/output_formatter/gitlab.rs b/apps/oxlint/src/output_formatter/gitlab.rs
index 98788abaf8e78..b5d3d7ce12c6b 100644
--- a/apps/oxlint/src/output_formatter/gitlab.rs
+++ b/apps/oxlint/src/output_formatter/gitlab.rs
@@ -1,4 +1,8 @@
 use std::hash::{DefaultHasher, Hash, Hasher};
+use std::path::{Path, PathBuf};
+
+#[cfg(windows)]
+use cow_utils::CowUtils;
 
 use serde::Serialize;
 
@@ -39,20 +43,66 @@ impl InternalFormatter for GitlabOutputFormatter {
     }
 }
 
+/// Find the git repository root by walking up from the current directory.
+/// Returns `None` if no `.git` directory is found.
+fn find_git_root() -> Option<PathBuf> {
+    let cwd = std::env::current_dir().ok()?;
+    find_git_root_from(&cwd)
+}
+
+/// Find the git repository root by walking up from the given path.
+fn find_git_root_from(start: &Path) -> Option<PathBuf> {
+    let mut current = start.to_path_buf();
+    loop {
+        if current.join(".git").exists() {
+            return Some(current);
+        }
+        if !current.pop() {
+            return None;
+        }
+    }
+}
+
+/// Get the path prefix from CWD to the git repository root.
+/// This prefix should be prepended to CWD-relative paths to make them repo-relative.
+///
+/// For example, if git root is `/repo` and CWD is `/repo/packages/foo`,
+/// this returns `Some("packages/foo")`.
+fn get_repo_path_prefix() -> Option<PathBuf> {
+    let cwd = std::env::current_dir().ok()?;
+    let git_root = find_git_root()?;
+
+    // Get the relative path from git root to CWD
+    let relative = cwd.strip_prefix(&git_root).ok()?;
+    if relative.as_os_str().is_empty() {
+        return None;
+    }
+
+    Some(relative.to_path_buf())
+}
+
 /// Renders reports as a Gitlab Code Quality Report
 ///
 /// <https://docs.gitlab.com/ci/testing/code_quality/#code-quality-report-format>
 ///
 /// Note that, due to syntactic restrictions of JSON arrays, this reporter waits until all
 /// diagnostics have been reported before writing them to the output stream.
-#[derive(Default)]
 struct GitlabReporter {
     diagnostics: Vec<Error>,
+    /// Path prefix to prepend to CWD-relative paths to make them repo-relative.
+    /// `None` if CWD is the git root or if we're not in a git repository.
+    repo_path_prefix: Option<PathBuf>,
+}
+
+impl GitlabReporter {
+    fn default() -> Self {
+        Self { diagnostics: Vec::new(), repo_path_prefix: get_repo_path_prefix() }
+    }
 }
 
 impl DiagnosticReporter for GitlabReporter {
     fn finish(&mut self, _: &DiagnosticResult) -> Option<String> {
-        Some(format_gitlab(&mut self.diagnostics))
+        Some(format_gitlab(&mut self.diagnostics, self.repo_path_prefix.as_deref()))
     }
 
     fn render_error(&mut self, error: Error) -> Option<String> {
@@ -61,7 +111,7 @@ impl DiagnosticReporter for GitlabReporter {
     }
 }
 
-fn format_gitlab(diagnostics: &mut Vec<Error>) -> String {
+fn format_gitlab(diagnostics: &mut Vec<Error>, repo_path_prefix: Option<&Path>) -> String {
     let errors = diagnostics.drain(..).map(|error| {
         let Info { start, end, filename, message, severity, rule_id } = Info::new(&error);
         let severity = match severity {
@@ -85,7 +135,23 @@ fn format_gitlab(diagnostics: &mut Vec<Error>) -> String {
             description: message,
             check_name: rule_id.unwrap_or_default(),
             location: GitlabErrorLocationJson {
-                path: filename,
+                // GitLab expects file paths to be relative to the repository
+                // root, so adjust accordingly.
+                path: match repo_path_prefix {
+                    Some(prefix) => {
+                        // only do the path swap on Windows
+                        #[cfg(windows)]
+                        {
+                            let combined = prefix.join(&filename);
+                            combined.to_string_lossy().cow_replace('\\', "/").into_owned()
+                        }
+                        #[cfg(not(windows))]
+                        {
+                            prefix.join(&filename).to_string_lossy().to_string()
+                        }
+                    }
+                    None => filename,
+                },
                 lines: GitlabErrorLocationLinesJson { begin: start.line, end: end.line },
             },
             fingerprint,
@@ -98,13 +164,15 @@ fn format_gitlab(diagnostics: &mut Vec<Error>) -> String {
 
 #[cfg(test)]
 mod test {
+    use std::path::{Path, PathBuf};
+
     use oxc_diagnostics::{
-        NamedSource, OxcDiagnostic,
+        Error, NamedSource, OxcDiagnostic,
         reporter::{DiagnosticReporter, DiagnosticResult},
     };
     use oxc_span::Span;
 
-    use super::GitlabReporter;
+    use super::{GitlabReporter, find_git_root_from, format_gitlab};
 
     #[test]
     fn reporter() {
@@ -112,7 +180,7 @@ mod test {
 
         let error = OxcDiagnostic::warn("error message")
             .with_label(Span::new(0, 8))
-            .with_source_code(NamedSource::new("file://test.ts", "debugger;"));
+            .with_source_code(NamedSource::new("test.ts", "debugger;"));
 
         let first_result = reporter.render_error(error);
 
@@ -133,9 +201,73 @@ mod test {
         assert!(value["fingerprint"].is_string()); // value is different on different architectures
         assert_eq!(value["severity"], "major");
         let location = value["location"].as_object().unwrap();
-        assert_eq!(location["path"], "file://test.ts");
+        assert_eq!(location["path"], "apps/oxlint/test.ts");
         let lines = location["lines"].as_object().unwrap();
         assert_eq!(lines["begin"], 1);
         assert_eq!(lines["end"], 1);
     }
+
+    #[test]
+    fn find_git_root_from_current_dir() {
+        // This test runs from within the oxc repo, so we should find a git root
+        let cwd = std::env::current_dir().unwrap();
+        let git_root = find_git_root_from(&cwd);
+        assert!(git_root.is_some());
+        assert!(git_root.unwrap().join(".git").exists());
+    }
+
+    #[test]
+    fn find_git_root_from_nonexistent() {
+        // A path that doesn't exist or has no git repo
+        let path = PathBuf::from("/");
+        let git_root = find_git_root_from(&path);
+        // Root directory typically doesn't have a .git folder
+        assert!(git_root.is_none() || *git_root.unwrap() == *"/");
+    }
+
+    #[test]
+    fn format_gitlab_with_prefix() {
+        let error = OxcDiagnostic::warn("test error")
+            .with_label(Span::new(0, 5))
+            .with_source_code(NamedSource::new("example.js", "const x = 1;"));
+
+        let mut diagnostics: Vec<Error> = vec![error];
+
+        // Test with a prefix
+        let result = format_gitlab(&mut diagnostics, Some(Path::new("packages/foo")));
+        let json: serde_json::Value = serde_json::from_str(&result).unwrap();
+        let path = json[0]["location"]["path"].as_str().unwrap();
+        assert_eq!(path, "packages/foo/example.js");
+    }
+
+    #[test]
+    fn format_gitlab_without_prefix() {
+        let error = OxcDiagnostic::warn("test error")
+            .with_label(Span::new(0, 5))
+            .with_source_code(NamedSource::new("example.js", "const x = 1;"));
+
+        let mut diagnostics: Vec<Error> = vec![error];
+
+        // Test without a prefix (CWD is at git root)
+        let result = format_gitlab(&mut diagnostics, None);
+        let json: serde_json::Value = serde_json::from_str(&result).unwrap();
+        let path = json[0]["location"]["path"].as_str().unwrap();
+        assert_eq!(path, "example.js");
+    }
+
+    #[cfg(windows)]
+    #[test]
+    fn format_gitlab_windows_normalization() {
+        let error = OxcDiagnostic::warn("test error")
+            .with_label(Span::new(0, 5))
+            .with_source_code(NamedSource::new("example.js", "const x = 1;"));
+
+        let mut diagnostics: Vec<Error> = vec![error];
+
+        // Windows-style prefix with backslashes should be normalized to forward slashes
+        let result = format_gitlab(&mut diagnostics, Some(Path::new(r"packages\foo")));
+        let json: serde_json::Value = serde_json::from_str(&result).unwrap();
+        let path = json[0]["location"]["path"].as_str().unwrap();
+        assert_eq!(path, "packages/foo/example.js");
+    }
 }
diff --git a/apps/oxlint/src/snapshots/fixtures__output_formatter_diagnostic_--format=gitlab --report-unused-disable-directives disable-directive.js@oxlint.snap b/apps/oxlint/src/snapshots/fixtures__output_formatter_diagnostic_--format=gitlab --report-unused-disable-directives disable-directive.js@oxlint.snap
index 50acf35fb3ed4..8544c875601bf 100644
--- a/apps/oxlint/src/snapshots/fixtures__output_formatter_diagnostic_--format=gitlab --report-unused-disable-directives disable-directive.js@oxlint.snap	
+++ b/apps/oxlint/src/snapshots/fixtures__output_formatter_diagnostic_--format=gitlab --report-unused-disable-directives disable-directive.js@oxlint.snap	
@@ -12,7 +12,7 @@ working directory: fixtures/output_formatter_diagnostic
     "fingerprint": "6460b46f54ac436d",
     "severity": "major",
     "location": {
-      "path": "disable-directive.js",
+      "path": "apps/oxlint/disable-directive.js",
       "lines": {
         "begin": 9,
         "end": 9
@@ -25,7 +25,7 @@ working directory: fixtures/output_formatter_diagnostic
     "fingerprint": "74c434632ebc59be",
     "severity": "major",
     "location": {
-      "path": "disable-directive.js",
+      "path": "apps/oxlint/disable-directive.js",
       "lines": {
         "begin": 12,
         "end": 12
@@ -38,7 +38,7 @@ working directory: fixtures/output_formatter_diagnostic
     "fingerprint": "9854c19736e51e0c",
     "severity": "major",
     "location": {
-      "path": "disable-directive.js",
+      "path": "apps/oxlint/disable-directive.js",
       "lines": {
         "begin": 15,
         "end": 15
diff --git a/apps/oxlint/src/snapshots/fixtures__output_formatter_diagnostic_--format=gitlab test.js@oxlint.snap b/apps/oxlint/src/snapshots/fixtures__output_formatter_diagnostic_--format=gitlab test.js@oxlint.snap
index 6a73c2a2ed634..047dc99b23175 100644
--- a/apps/oxlint/src/snapshots/fixtures__output_formatter_diagnostic_--format=gitlab test.js@oxlint.snap	
+++ b/apps/oxlint/src/snapshots/fixtures__output_formatter_diagnostic_--format=gitlab test.js@oxlint.snap	
@@ -12,7 +12,7 @@ working directory: fixtures/output_formatter_diagnostic
     "fingerprint": "9333a3278325994",
     "severity": "critical",
     "location": {
-      "path": "test.js",
+      "path": "apps/oxlint/test.js",
       "lines": {
         "begin": 5,
         "end": 5
@@ -25,7 +25,7 @@ working directory: fixtures/output_formatter_diagnostic
     "fingerprint": "b1e9b343a9c1e457",
     "severity": "major",
     "location": {
-      "path": "test.js",
+      "path": "apps/oxlint/test.js",
       "lines": {
         "begin": 1,
         "end": 1
@@ -38,7 +38,7 @@ working directory: fixtures/output_formatter_diagnostic
     "fingerprint": "53ecf7c08335f91",
     "severity": "major",
     "location": {
-      "path": "test.js",
+      "path": "apps/oxlint/test.js",
       "lines": {
         "begin": 1,
         "end": 1