MacDonald graduated from Concordia University (Loyola) in 1969 with an honours degree in political science.

He wrote his first book in 1984, a bestseller that covered Brian Mulroney's rise from boyhood to Prime Minister of Canada. MacDonald served as chief speechwriter for Mulroney from 1985–88. He served as Minister of Public Affairs at the Canadian Embassy in Washington, DC from 1992–94.

MacDonald has published four more books. most recently "Politics, People & Potpourri", selected by CBC as as "one of the best political reads" of 2009. He writes frequently for Canadian newspapers, including The Montreal Gazette and Sun Media, and broadcasts on radio and television. He serves as editor in chief of the periodical Policy Options, published by the Institute for Research on Public Policy.