One of three sons, Findley was born in Toronto, Ontario, to Allan Gilmour Findley, a stockbroker, and his wife, the former Margaret Maude Bull. His paternal grandfather was President of Massey-Harris, the farm-machinery company. He was raised in the upper class Rosedale district of the city, attending boarding school at St. Andrew's College (although leaving during grade 10 for health reasons). He pursued a career in the arts, studying dance and acting, and had significant success as an actor before turning to writing. He was part of the original Stratford Festival company in the 1950s, acting alongside Alec Guinness, and appeared in the first production of Thornton Wilder's The Matchmaker at the Edinburgh Festival. He also played Peter Pupkin in Sunshine Sketches, the CBC Television adaptation of Stephen Leacock's Sunshine Sketches of a Little Town.