Sir William Trelawny, 6th Baronet (c. 1722 – 11 December 1772), of Trelawne, Cornwall was a British politician and colonial administrator.

He succeeded his uncle Sir Harry Trelawny, 5th Baronet to the baronetcy in 1762, inheriting the Trelawne estate.

Trelawny sat as Member of Parliament for West Looe from 1757 to 1767.

The latter year he was appointed Governor of Jamaica, a post he held until his death in December 1772.

He had married his cousin Laetitia, the daughter and heiress of Sir Harry Trelawny, 5th Baronet, with whom he had a son and a daughter.