He graduated from St. Francis Xavier University, where he met and became close friends with future prime minister Brian Mulroney, and went on to earn his law degree at Dalhousie University.
In the general election of 1963, he was elected to the Nova Scotia House of Assembly as a Progressive Conservative representing the provincial riding of Richmond. He was re-elected in 1967 and 1970.
He ran for leader of the Progressive Conservative Party of Nova Scotia in the party's 1971 leadership convention, finishing second to John Buchanan.
Starting in 1984, Gerald Doucet was a member of the successful but sometimes controversial Ottawa consulting firm Government Consultants International (GCI), along with Frank Moores, Francis Fox, and Gary Ouellet (The Insiders, by John Sawatsky, 1987; On The Take, by Stevie Cameron, 1994).
In 2004 he published his biography, "Acadian Footprints".
He is the brother of Fred Doucet, who served as the first Chief of Staff to Brian Mulroney, after Mulroney became leader of the Progressive Conservative Party in 1983. Fred Doucet is a longtime associate of Mulroney, and served on his staff in the Prime Minister's Office while Mulroney was Canadian Prime Minister from 1984-1993.