St Catherine's Lighthouse is situated at Niton Undercliffe, 8 km (5 miles) from Ventnor on the Isle of Wight and comprises a white octagonal tower with 94 steps up to the lantern. The main light, visible for up to 48 km (30 miles) in clear weather is the third most powerful light in the Trinity House Service giving a guide to shipping in the Channel as well as vessels approaching the Solent.

There is a fixed red subsidiary light displayed from a window 7 metres (56 ft) below the main light and shown westward over the Atherfield Ledge. It is visible for 27 km (17 miles) in clear weather, and was first exhibited in 1904. Both lights are electric, and standby battery lights are provided in case of a power failure.

A small light was first set up at St. Catherine's in about 1323 by Walter de Godyton. He erected a chapel and added an endowment for a priest to say Masses for his family and to exhibit lights at night to warn ships from approaching too near this dangerous coast, both purposes being fulfilled until about 1530 when the Reformation swept away the endowment. Neither the present lighthouse tower lighted in March 1840, nor the chapel of which the ruins remain, held these ancient lights.

The present tower was constructed in 1838 following the loss of the sailing ship 'Clarendon' on rocks near the site of the present lighthouse. The lighthouse was built of ashlar stone with dressed quoins and was carried up from a base plinth as a three tier octagon, diminishing by stages. The elevation of the light proved to be too high, as the lantern frequently became mist capped and in 1875 it was decided to lower the light 13 metres (43 ft) by taking about 6 metres (20 ft) out of the uppermost section of the tower and about 7 metres (23 ft) out of the middle tier, which destroyed its beauty and made it appear dwarfed.

At that time the fog signal house was situated near the edge of the cliff but owing to erosion and cliff settlements the building developed such serious cracks that in 1932 it became necessary to find a new place for the fog signal, which was eventually mounted on a lower tower annexed to the front of the lighthouse tower, and built as a small replica. The resultant effect has been to give a well proportioned step down between the two towers which are now expressively referred to by the local inhabitants as "The Cow and the Calf". The fog signal was discontinued in 1987.

A tragic incident took place at the station during the Second World War. On the 1st June 1943 a bombing raid destroyed the engine house killing the three keepers on duty who had taken shelter in the building. R.T. Grenfell, C. Tomkins and W.E. Jones were buried in the local cemetery at Niton village and a plaque in remembrance of them is displayed on the ground floor of the main tower.

St Catherine's Lighthouse was automated in 1997 with the keepers leaving the lighthouse on 30 July.