King succeeded Tobi Nussbaum as councillor for Rideau-Rockcliffe Ward in the 2019 Rideau-Rockcliffe municipal by-election.[9] King had previously run in Rideau-Rockcliffe in the 2010 municipal election and ran for a trustee seat on the Ottawa-Carleton District School Board in the 2018 municipal election. He was unsuccessful on both occasions.
In his successful by-election bid, King was endorsed by a number of high-profile progressives in Ottawa. Once elected, King identified his priorities as developing a poverty reduction strategy for impoverished neighbourhoods; working to improve roads, public transit and social services; and improving the relationship of people of colour with the police.[10]
During his first term, King served as Chair of the Built Heritage Sub-Committee and on the Standing Committee on Environmental Protection, Water and Waste Management. He also served on the boards of Crime Prevention Ottawa, Ottawa Community Housing Corporation, Ottawa Community Lands Development Corporation and Quartier Vanier BIA. He was formerly on the Ottawa Police Services Board, before resigning in protest following the removal of board chair Diane Deans in the wake of Ottawa "Freedom Convoy".[11]
To advance anti-racism and race relations initiatives in 2020, King was appointed Council Liaison for Anti-Racism and Ethnocultural Relations Initiatives, where he was successful in establishing an anti-racism office and the city's first anti-racism strategy.[12]
He was re-elected in a landslide victory in 2022 with over 80 percent of the popular vote in a four-person field and a 72 percent margin of victory.[13]
During his second term, King was appointed Chair of the Built Heritage Committee and served on the Finance and Corporate Services Committee, Environment and Climate Change Committee, and the Community Services Committee. He was also appointed to the boards of Ottawa Public Health, the Ottawa Public Library and Quartier Vanier BIA. King was also reappointed Council Liaison for the City’s Anti-Racism and Ethnocultural Relations Initiatives, leading the implementation of the City of Ottawa's Anti-Racism Strategy.
King endorsed Yasir Naqvi in his candidacy for leader of the Ontario Liberal Party in the 2023 Ontario Liberal Party leadership election.[14]