Harvey played minor league hockey in his native Montreal, Quebec, Canada, then began his professional career with the Montreal Royals of the Quebec Senior Hockey League where he played from 1945 to 1947, helping them win the Allan Cup. He then played one season with the Buffalo Bisons of the American Hockey League. He made the jump to the Montreal Canadiens of the NHL in the 1947-48 NHL season with whom he remained until 1961.

Under coach Dick Irvin, Harvey was named to the All-Star team 11 consecutive times, beginning in the 1951-52 NHL season. He won his first of seven James Norris Memorial Trophys in 1955 as the league's best defenseman. In an era when the defensemen's role did not include scoring points, Harvey used his skating speed and passing ability to become a factor in making the Canadiens a high-scoring team. He had such puck control that by himself he could set the pace of the game.

He earned six Stanley Cups, all with Montreal. In 1954, however, he "scored" the Cup-winning goal for the Detroit Red Wings when he tipped the puck shot by a Red Wing past goalie Gerry McNeil. McNeil was so crushed by the Harvey "goal," he retired to coach junior hockey the next season, but returned to the Habs in 1956 as back-up to Hall of Famer Jacques Plante.

Harvey became an outspoken critic of the hockey establishment who "owned" players for life. In Harvey’s day, players were paid a pittance compared to the millions being earned by the team owners. A superstar such as Harvey, who today would be paid millions, was earning less than $30,000 a season at the peak of his career while playing every game in front of sell-out crowds. Harvey was one of the first to help organize the players association which so infuriated the Canadiens’ owners that in 1961 they traded him to the then lowly New York Rangers. One of the individuals secretly blacklisted by the league owners, Harvey still responded by winning another Norris Trophy as a Ranger. He remained with New York until 1963 then played for several teams before finishing his NHL career in 1969 with the St. Louis Blues.

Well into his forties, and with limited education and no other skills besides hockey, Harvey eked out a living playing in the minor-pro leagues and with an assistant coaching tenure in the World Hockey Association. Although he was unanimously voted into the Hockey Hall of Fame in 1973, because of his involvement with the players' association, his sweater number wasn't retired by the Montreal Canadiens until 1985.

For years, Harvey battled alcoholism while suffering from bipolar disorder. In one of the great tragedies of sports, one of the preeminent stars in the history of hockey ended up homeless, sleeping in an abandoned railway boxcar. When his plight became public knowledge, in 1985 he was offered a job with the Montreal Canadiens as a scout. He died a few years later due to cirrhosis of the liver and was interred in the Notre-Dame-des-Neiges Cemetery in Montreal.

The government of Canada honored Doug Harvey in 2000 with his image placed on a Canadian postage stamp.

In 2002, a book on his life was published. Titled Doug: The Doug Harvey Story, it was written by William Brown with a foreword by his former teammate, Jean Béliveau.

His jersey number (#2) was retired on October 26, 1985.