William Tetley attended the Royal Canadian Naval College and served with the Royal Canadian Navy. He graduated from McGill University with a bachelor's degree then obtained a law degree from Université Laval. He was admitted to the Bar of Quebec in 1952, a year he also began contributing to the Montreal Star and the Montreal Gazette newspapers as a literary critic. He is also the author of books and has written a number of articles on public affairs and legal matters for Canadian, United Kingdom and Americannewspapers. Active in the Boy Scouts of Canada for many years, in 1969 William Tetley was awarded the Boy Scouts of Canada Medal. As well, he served the Montreal community as a board member and chairman of the city's International Branch of the YMCA.
In 1995, William Tetley was made a Member of the Order of Canada. In December 2006, his book The October Crisis, 1970: An Insider's View was published by McGill-Queen's University Press.