He served in the Legislative Assembly of Ontario as a member of the Progressive Conservative Party from 1963 to 1985 and was a cabinet minister in the governments of John Robarts and William Davis.

Wells and William Davis played on the University of Toronto's football team at the same time and were both members of the campus Progressive Conservative association.

When Davis succeeded Robarts as Premier of Ontario on March 1, 1971, he named Wells as his Minister of Social and Family Services.

[9] Shortly after his appointment, Wells permitted Ontario schoolchildren to watch the final game of the 1972 "Summit Series" ice hockey tournament between Canada and the Soviet Union from their classrooms.

Both Wells and Davis were prominent supporters of Liberal Prime Minister Pierre Elliott Trudeau's plans to repatriate the Canadian Constitution, and were active in the negotiations that led to its adoption in 1982.

A street within the Heathwood Community in Scarborough near the intersection of Birchmount Road and Sanwood Boulevard has been named after Thomas Leonard Wells.