Named after Lord William Bentinck (1774-1839), Whig (Liberal) politician, who was the first governor general of British-occupied India and a friend of the Prime Minister of the time, Benjamin Disraeli (John J. Marshall, Belfast Telegraph, 03/03/1941). He was British governor-general of Bengal 1828-33, and of India 1833-35. He is credited with initiating important social and educational reforms. He introduced legislation to ban the practice of sati, the burning of a widow on the funeral pyre of her deceased husband. Note that the dates given by Marshall for his birth and death are wildly incorrect.
The name originally approved for this street was Bentwick Street. Shortly afterwards it was changed to Bentinck Street, which may well reflect the original naming intention, as Bentwick is not known as a place-name or surname. The street features in the 1856 Belfast Street Directory with the listing (Off York Road). Several entries contain the word “vacant”.
Lord William Bentinck | British Governor-General of India | Britannica