In 1962, Davis was elected to the Canadian House of Commons representing the riding of Coast—Capilano, a riding which stretched from Deep Cove in the District of North Vancouver to Powell River and Pemberton. A member of the then-minority Liberal Party of Canada, he was re-elected in the following year in the train of the national Liberal victory and was appointed as the Parliamentary Secretary to Prime Minister Lester B. Pearson. Davis was re-elected in the Canadian federal elections of 1965 and 1968 (now in the riding of Capilano (electoral district) and 1972. A cabinet minister in the government of Pierre Elliott Trudeau, he was Minister without Portfolio, Minister of Fisheries, Minister of Fisheries and Forestry, and the first Minister of the Environment in the English-speaking world. He was defeated in the Canadian federal election of 1974.