Born in Fort William in 1916, Murdo's first success came as a member of the 1935-36 Fort William Kams Junior District championship team. A fast starter who could reach peak speed in a few strides, he was signed by the New York Rovers of the Eastern Amateur Hockey League (EHL) in 1936. A high scorer who netted many hat-tricks, he helped his team claim the league title in 1939-40 and was named an EHL All-Star.

Joining the American Hockey League (AHL) with the Philadelphia Ramblers in 1940-41, he moved to the Buffalo Bisons the following year. Enlisting for the war effort, he served in the Navy from 1942-45, playing hockey in British Columbia and Halifax. Following the war, Murdo returned to Buffalo where he contributed to the Bison's 1945-46 Calder Cup victory as AHL Champions.

The 1945-46 season also saw Murdo's first introduction to the NHL, with the Montreal Canadiens calling him up during the regular season. The Canadiens would continue to call upon Murdo for the next three seasons including the 1948-49 Stanley Cup playoffs, where he netted the deciding goal in the third game against Detroit in the semi-finals.

In 1948-49 Murdo led Buffalo in scoring, was 6th overall in the AHL and was named to the AHL All-Star Team, having amassed 84 points that season. The following season he netted his 200th AHL goal, becoming only the 5th player in the AHL to do so. In 1949-50 Murdo entered the record books again, becoming the first person in the AHL to have scored 30 or more goals for 5 consecutive seasons. Moving to the Cleveland Barons in 1950-51, Murdo finished up his AHL career with a second Calder Cup League title. The 1951-52 season added a Quebec Senior Hockey League (QSHL) title to his record with the Quebec Aces. After one more year in Quebec, Murdo hung up his skates, bringing to a close a successful hockey career which had begun over 20 years earlier in Fort William.

Throughout his career, Murdo was not only one of the most feared centreman in the game, but was also a fan favourite. As one Buffalo reporter noted, "There was something electric about a MacKay rush down the centre of the ice". A fine tribute to a fine hockey player.

Inducted into the Northwestern Ontario Sports Hall of Fame, September 25, 1999