diff --git a/apps/oxfmt/src/core/utils.rs b/apps/oxfmt/src/core/utils.rs
index bcff2dd0dea80..44329b536efac 100644
--- a/apps/oxfmt/src/core/utils.rs
+++ b/apps/oxfmt/src/core/utils.rs
@@ -59,12 +59,24 @@ pub fn print_and_flush(writer: &mut dyn Write, message: &str) {
     writer.flush().unwrap();
 }
 
-/// Normalize a relative path by stripping `./` prefix and joining with `cwd`.
-/// This ensures consistent path format and avoids issues with relative paths.
+/// Normalize a relative path by:
+/// - stripping `./` prefix,
+/// - joining with `cwd`,
+/// - and canonicalizing to resolve `..` components
+///
+/// This ensures consistent absolute path format,
+/// which is required for gitignore-based pattern matching
+/// (e.g., `ignorePatterns` resolution).
 pub fn normalize_relative_path(cwd: &Path, path: &Path) -> PathBuf {
     if path.is_absolute() {
         return path.to_path_buf();
     }
 
-    if let Ok(stripped) = path.strip_prefix("./") { cwd.join(stripped) } else { cwd.join(path) }
+    let joined = if let Ok(stripped) = path.strip_prefix("./") {
+        cwd.join(stripped)
+    } else {
+        cwd.join(path)
+    };
+
+    fs::canonicalize(&joined).unwrap_or(joined)
 }
diff --git a/apps/oxfmt/test/cli/config_ignore_patterns/__snapshots__/config_ignore_patterns.test.ts.snap b/apps/oxfmt/test/cli/config_ignore_patterns/__snapshots__/config_ignore_patterns.test.ts.snap
index a71e3402d656b..6535f0eafc493 100644
--- a/apps/oxfmt/test/cli/config_ignore_patterns/__snapshots__/config_ignore_patterns.test.ts.snap
+++ b/apps/oxfmt/test/cli/config_ignore_patterns/__snapshots__/config_ignore_patterns.test.ts.snap
@@ -1,5 +1,22 @@
 // Vitest Snapshot v1, https://vitest.dev/guide/snapshot.html
 
+exports[`config_ignore_patterns > explicit --config with parent-relative path resolves ignorePatterns correctly 1`] = `
+"--------------------
+arguments: --check --config ../.oxfmtrc.json .
+working directory: config_ignore_patterns/fixtures/nested_cwd/sub
+exit code: 1
+--- STDOUT ---------
+Checking formatting...
+
+src/test.js (<variable>ms)
+
+Format issues found in above 1 files. Run without \`--check\` to fix.
+Finished in <variable>ms on 1 files using 1 threads.
+--- STDERR ---------
+
+--------------------"
+`;
+
 exports[`config_ignore_patterns > nested cwd - ignorePatterns resolved relative to .oxfmtrc.json location 1`] = `
 "--------------------
 arguments: --check .
diff --git a/apps/oxfmt/test/cli/config_ignore_patterns/config_ignore_patterns.test.ts b/apps/oxfmt/test/cli/config_ignore_patterns/config_ignore_patterns.test.ts
index 32a46b3a30c62..44041db64aa0a 100644
--- a/apps/oxfmt/test/cli/config_ignore_patterns/config_ignore_patterns.test.ts
+++ b/apps/oxfmt/test/cli/config_ignore_patterns/config_ignore_patterns.test.ts
@@ -34,4 +34,20 @@ describe("config_ignore_patterns", () => {
     const snapshot = await runAndSnapshot(nestedCwd, [["--check", "."]]);
     expect(snapshot).toMatchSnapshot();
   });
+
+  // Same structure as above, but explicitly specifying `--config ../.oxfmtrc.json`
+  // instead of relying on automatic upward config search.
+  //
+  // When `--config` contains `..`, `normalize_relative_path` joins
+  // cwd + `../.oxfmtrc.json` without resolving `..`, leaving the path as
+  // `.../sub/../.oxfmtrc.json`. This causes `GitignoreBuilder`'s root
+  // to be `.../sub/..` which doesn't match file paths via `strip_prefix`,
+  // making `ignorePatterns` ineffective.
+  it("explicit --config with parent-relative path resolves ignorePatterns correctly", async () => {
+    const nestedCwd = join(import.meta.dirname, "fixtures", "nested_cwd", "sub");
+    const snapshot = await runAndSnapshot(nestedCwd, [
+      ["--check", "--config", "../.oxfmtrc.json", "."],
+    ]);
+    expect(snapshot).toMatchSnapshot();
+  });
 });
diff --git a/apps/oxfmt/test/cli/config_ignore_patterns/fixtures/nested_cwd/generated/error.html b/apps/oxfmt/test/cli/config_ignore_patterns/fixtures/nested_cwd/generated/error.html
new file mode 100644
index 0000000000000..83fe83255b0eb
--- /dev/null
+++ b/apps/oxfmt/test/cli/config_ignore_patterns/fixtures/nested_cwd/generated/error.html
@@ -0,0 +1 @@
+<link rel=stylesheet href=/styles.css />
diff --git a/apps/oxfmt/test/cli/config_ignore_patterns/fixtures/nested_cwd/generated/ignored.js b/apps/oxfmt/test/cli/config_ignore_patterns/fixtures/nested_cwd/generated/ignored.js
deleted file mode 100644
index 6dd369d986dfb..0000000000000
--- a/apps/oxfmt/test/cli/config_ignore_patterns/fixtures/nested_cwd/generated/ignored.js
+++ /dev/null
@@ -1,2 +0,0 @@
-// This file should be ignored
-const x=1
diff --git a/apps/oxfmt/test/cli/config_ignore_patterns/fixtures/nested_cwd/sub/generated/error.html b/apps/oxfmt/test/cli/config_ignore_patterns/fixtures/nested_cwd/sub/generated/error.html
new file mode 100644
index 0000000000000..83fe83255b0eb
--- /dev/null
+++ b/apps/oxfmt/test/cli/config_ignore_patterns/fixtures/nested_cwd/sub/generated/error.html
@@ -0,0 +1 @@
+<link rel=stylesheet href=/styles.css />
diff --git a/apps/oxfmt/test/cli/config_ignore_patterns/fixtures/nested_cwd/sub/generated/ignored.js b/apps/oxfmt/test/cli/config_ignore_patterns/fixtures/nested_cwd/sub/generated/ignored.js
deleted file mode 100644
index 6dd369d986dfb..0000000000000
--- a/apps/oxfmt/test/cli/config_ignore_patterns/fixtures/nested_cwd/sub/generated/ignored.js
+++ /dev/null
@@ -1,2 +0,0 @@
-// This file should be ignored
-const x=1