diff --git a/Tests/LibWeb/Text/expected/geometry/dommatrix.txt b/Tests/LibWeb/Text/expected/geometry/dommatrix.txt
index 146a39da144..d928e142cc9 100644
--- a/Tests/LibWeb/Text/expected/geometry/dommatrix.txt
+++ b/Tests/LibWeb/Text/expected/geometry/dommatrix.txt
@@ -10,3 +10,5 @@
 10. {"a":10,"b":20,"c":31.76326980708465,"d":43.5265396141693,"e":50,"f":60,"m11":10,"m12":20,"m13":0,"m14":0,"m21":31.76326980708465,"m22":43.5265396141693,"m23":0,"m24":0,"m31":0,"m32":0,"m33":1,"m34":0,"m41":50,"m42":60,"m43":0,"m44":1,"is2D":true,"isIdentity":false}
 11. {"a":15.289809421253949,"b":27.0530792283386,"c":30,"d":40,"e":50,"f":60,"m11":15.289809421253949,"m12":27.0530792283386,"m13":0,"m14":0,"m21":30,"m22":40,"m23":0,"m24":0,"m31":0,"m32":0,"m33":1,"m34":0,"m41":50,"m42":60,"m43":0,"m44":1,"is2D":true,"isIdentity":false}
 12. {"a":15.289809421253949,"b":27.0530792283386,"c":30,"d":40,"e":50,"f":60,"m11":15.289809421253949,"m12":27.0530792283386,"m13":0,"m14":0,"m21":30,"m22":40,"m23":0,"m24":0,"m31":0,"m32":0,"m33":1,"m34":0,"m41":50,"m42":60,"m43":0,"m44":1,"is2D":true,"isIdentity":false}
+13. {"a":-10,"b":-20,"c":30,"d":40,"e":50,"f":60,"m11":-10,"m12":-20,"m13":0,"m14":0,"m21":30,"m22":40,"m23":0,"m24":0,"m31":0,"m32":0,"m33":1,"m34":0,"m41":50,"m42":60,"m43":0,"m44":1,"is2D":true,"isIdentity":false}
+14. {"a":10,"b":20,"c":-30,"d":-40,"e":50,"f":60,"m11":10,"m12":20,"m13":0,"m14":0,"m21":-30,"m22":-40,"m23":0,"m24":0,"m31":0,"m32":0,"m33":1,"m34":0,"m41":50,"m42":60,"m43":0,"m44":1,"is2D":true,"isIdentity":false}
diff --git a/Tests/LibWeb/Text/input/geometry/dommatrix.html b/Tests/LibWeb/Text/input/geometry/dommatrix.html
index 981bc2d2620..9e39d68771b 100644
--- a/Tests/LibWeb/Text/input/geometry/dommatrix.html
+++ b/Tests/LibWeb/Text/input/geometry/dommatrix.html
@@ -41,5 +41,11 @@
 
         // 12. Skew Y DOMMatrix with multiply
         testPart(() => new DOMMatrix([10, 20, 30, 40, 50, 60]).multiply(new DOMMatrix().skewY(10)));
+
+        // 13. Flip X DOMMatrix
+        testPart(() => new DOMMatrix([10, 20, 30, 40, 50, 60]).flipX());
+
+        // 14. Flip Y DOMMatrix
+        testPart(() => new DOMMatrix([10, 20, 30, 40, 50, 60]).flipY());
     });
 </script>
diff --git a/Userland/Libraries/LibWeb/Geometry/DOMMatrixReadOnly.cpp b/Userland/Libraries/LibWeb/Geometry/DOMMatrixReadOnly.cpp
index 948f3229c36..45f8d08b0b7 100644
--- a/Userland/Libraries/LibWeb/Geometry/DOMMatrixReadOnly.cpp
+++ b/Userland/Libraries/LibWeb/Geometry/DOMMatrixReadOnly.cpp
@@ -284,6 +284,44 @@ WebIDL::ExceptionOr<JS::NonnullGCPtr<DOMMatrix>> DOMMatrixReadOnly::multiply(DOM
     return result->multiply_self(other);
 }
 
+// https://drafts.fxtf.org/geometry/#dom-dommatrixreadonly-flipx
+JS::NonnullGCPtr<DOMMatrix> DOMMatrixReadOnly::flip_x()
+{
+    // 1. Let result be the resulting matrix initialized to the values of the current matrix.
+    auto result = DOMMatrix::create_from_dom_matrix_read_only(realm(), *this);
+
+    // 2. Post-multiply result with new DOMMatrix([-1, 0, 0, 1, 0, 0]).
+    // clang-format off
+    Gfx::DoubleMatrix4x4 flip_matrix = { -1, 0, 0, 0,
+        0, 1, 0, 0,
+        0, 0, 1, 0,
+        0, 0, 0, 1 };
+    // clang-format on
+    result->m_matrix = result->m_matrix * flip_matrix;
+
+    // 3. Return result.
+    return result;
+}
+
+// https://drafts.fxtf.org/geometry/#dom-dommatrixreadonly-flipy
+JS::NonnullGCPtr<DOMMatrix> DOMMatrixReadOnly::flip_y()
+{
+    // 1. Let result be the resulting matrix initialized to the values of the current matrix.
+    auto result = DOMMatrix::create_from_dom_matrix_read_only(realm(), *this);
+
+    // 2. Post-multiply result with new DOMMatrix([1, 0, 0, -1, 0, 0]).
+    // clang-format off
+    Gfx::DoubleMatrix4x4 flip_matrix = { 1, 0, 0, 0,
+        0, -1, 0, 0,
+        0, 0, 1, 0,
+        0, 0, 0, 1 };
+    // clang-format on
+    result->m_matrix = result->m_matrix * flip_matrix;
+
+    // 3. Return result.
+    return result;
+}
+
 // https://drafts.fxtf.org/geometry/#dom-dommatrixreadonly-inverse
 JS::NonnullGCPtr<DOMMatrix> DOMMatrixReadOnly::inverse() const
 {
diff --git a/Userland/Libraries/LibWeb/Geometry/DOMMatrixReadOnly.h b/Userland/Libraries/LibWeb/Geometry/DOMMatrixReadOnly.h
index 6b7d2e5769b..41025d20d70 100644
--- a/Userland/Libraries/LibWeb/Geometry/DOMMatrixReadOnly.h
+++ b/Userland/Libraries/LibWeb/Geometry/DOMMatrixReadOnly.h
@@ -88,6 +88,8 @@ public:
     JS::NonnullGCPtr<DOMMatrix> skew_x(double sx = 0) const;
     JS::NonnullGCPtr<DOMMatrix> skew_y(double sy = 0) const;
     WebIDL::ExceptionOr<JS::NonnullGCPtr<DOMMatrix>> multiply(DOMMatrixInit other = {});
+    JS::NonnullGCPtr<DOMMatrix> flip_x();
+    JS::NonnullGCPtr<DOMMatrix> flip_y();
     JS::NonnullGCPtr<DOMMatrix> inverse() const;
 
     JS::NonnullGCPtr<DOMPoint> transform_point(DOMPointInit const&) const;
diff --git a/Userland/Libraries/LibWeb/Geometry/DOMMatrixReadOnly.idl b/Userland/Libraries/LibWeb/Geometry/DOMMatrixReadOnly.idl
index 2b25fad8de9..6a5651bbb10 100644
--- a/Userland/Libraries/LibWeb/Geometry/DOMMatrixReadOnly.idl
+++ b/Userland/Libraries/LibWeb/Geometry/DOMMatrixReadOnly.idl
@@ -49,8 +49,8 @@ interface DOMMatrixReadOnly {
     [NewObject] DOMMatrix skewX(optional unrestricted double sx = 0);
     [NewObject] DOMMatrix skewY(optional unrestricted double sy = 0);
     [NewObject] DOMMatrix multiply(optional DOMMatrixInit other = {});
-    // FIXME: [NewObject] DOMMatrix flipX();
-    // FIXME: [NewObject] DOMMatrix flipY();
+    [NewObject] DOMMatrix flipX();
+    [NewObject] DOMMatrix flipY();
     [NewObject] DOMMatrix inverse();
 
     [NewObject] DOMPoint transformPoint(optional DOMPointInit point = {});