Macnaughton first won a seat in the House of Commons of Canada in the 1949 election, when he was returned as a Liberal Member of Parliament (MP) for the riding of Mount Royal.
He established four subcommittees of the Special Committee on Procedure and Organization, each chaired by a member of a different political party (Liberal, Progressive-Conservative, Social Credit, and New Democrat).
The result of this process were recommendations for new procedures of time allocation in debates, a new committee structure, the abolition of the right to appeal rulings of the Speaker, research budgets for members and other changes, most of which were ultimately implemented.
Late in his term as Speaker, he served as a production consultant on the politically-themed CBC Television drama series Quentin Durgens, M.P..[1] Macnaughton did not contest the 1965 election, and retired from electoral politics.
In 1966, Prime Minister Lester B. Pearson recommended that Macnaughton be appointed to a seat in the Senate of Canada.