St Mary's Lifeboat Station is situated in St Mary's Harbour, Isles of Scilly and has been an important station for the Royal National Lifeboat Institution since the service began in 1837, however without a service between 1855 and 1874.

A lifeboat station was provided in 1874 at a cost of £280 (equivalent to £32,800 in 2023). In 1899 this was replaced by a new station at Carn Thomas with a slipway, at a cost of £1,500 (equivalent to £213,300 in 2023). In 1902 the slipway was extended by 40 feet (12 m) by Robert Hicks to enable the lifeboat to be launched at any state of the tide.

The lifeboat house was adapted in 1914 to receive a new motor lifeboat, but this didn't arrive on the station until 1919.

Since the arrival of the Robert Edgar in 1981, the lifeboat has been moored in the harbour, rather than the lifeboat house.

At St Mary's	ON	Op. No.	Name	Class	Comments
1837–1839	—	—	(no name)	Plenty	20 ft (6.1 m) lifeboat, originally built for Brighton.
1840–1855	—	—	(no name)	Plenty	26 ft (7.9 m) lifeboat, originally built for Plymouth.
1874–1890	—	—	Henry Dundas	Self-Righter	37 feet (11 m) long, 9 feet (2.7 m) wide with rows of 12 oars, double-banked. Paid for by Mrs. S.J. Dundas.
1890–1991	271	—	Henry Dundas	Self-Righter	42 ft 7 in (12.98 m) lifeboat. Later renamed Tom & Jenny.
1891–1899	313	—	Henry Dundas	Self-Righter	38 feet (12 m) long and 8 feet (2.4 m) wide.
1899–1919	434	—	Henry Dundas	Watson	38 ft (12 m) non-self-righting lifeboat.
1919–1930	648	—	Elsie	Watson	First motor lifeboat at station. 45 ft (14 m) long and 12 ft 6 in (3.81 m) wide with a 60 BHP Tylor motor and Gardner reverse gear, giving a speed of 8 knots (9.2 mph; 15 km/h).
1930–1953	728	—	Cunard	Watson	45 ft 6 in (13.87 m) motor lifeboat. Given by the Cunard Steamship Company. Two 40 hp engines giving a speed of 8.25 knots (9.49 mph; 15.28 km/h). Cost £8,500 (equivalent to £678,800 in 2023).
1955–1981	926	—	Guy and Clare Hunter	Watson	Last slipway launched boat. 46 ft 9 in (14.25 m) long, speed 8 knots (9.2 mph; 15 km/h). Cost £32,000 (equivalent to £1,060,400 in 2023).
1981–1997	1073	52-18	Robert Edgar	Arun	Sold in 2002 for use as a training boat in New Zealand.
1997–	1229	17-11	The Whiteheads	Severn

St Mary's Lifeboat has received fifty-six awards for gallantry, including 26 RNLI medals for bravery, comprising one gold, nine silver and 16 bronze. The most recent was in 2004 when bronze medals were awarded to Coxswain Andrew Howells and Crew Members Mark Bromham and Philip Roberts for the rescue of an injured man from a yacht on 29 October 2003.

• St Agnes Lifeboat Station (Isles of Scilly)
• List of RNLI stations

• RNLI station information