He was a New Democratic member of the House of Commons of Canada from 2011 to 2015 who was elected to represent the Toronto riding of York South—Weston.

From February 1974 to November 1984, he worked for Canadian Broadcasting Corporation (CBC) where he was radio master control operator.

[3][4] He served as the NDP's Deputy Critic for Housing and Disability Issues in the 41st Canadian Parliament.

In the 2015 election, Sullivan lost his seat to Liberal candidate Ahmed Hussen by 7,622 votes.

[5] After losing his seat, he endorsed Charlie Angus in the 2017 New Democratic Party leadership election.