St Ninian's Chapel is a ruined chapel, located on the seaward side of the Isle of Whithorn, Dumfries and Galloway.
The chapel and enclosure wall were built in 1300, on the site of a narrower chapel dedicated to St Ninian in the 1200 century, comprised a small nave and a separate, narrower chancel. It stood within a stone enclosure wall, part of which is still standing today. There was also a stone bench, presumably for use by weary pilgrims who had landed in the bay, then visited the chapel to give thanks for a safe journey, on their pilgrimage to Whithorn Priory.
In 1864, dressed stone facing the walls of the chapel was taken by a retired sea captain for reuse in the construction of his nearby home.
The chapel was repaired and partly rebuilt in 1898 by the Marquess of Bute.