Patrick was born in Victoria, British Columbia. In his youth, Muzz Patrick was one of Canada's most versatile athletes, excelling in track, basketball, football, cycling, boxing and hockey. In the ring, he was a Canadian amateur light heavyweight champion. But having Lester Patrick, the original coach and GM of the New York Rangers, for a father, lent a heavy bias towards pursuing hockey as a career. His brother, Lynn Patrick, was also an NHL player.
Patrick turned pro with the New York Crescents in 1934 and then jumped to the Rovers the next year. There he played with future NHLers Alex Shibicky and the Colville brothers, Neil and Mac. After a two-year stint with the Philadelphia Ramblers of the AHL, Patrick finally settled in for full-time NHL action in 1938 with the Rangers. It was there that he used his large frame and boxing skills to keep opponents honest in the Rangers' zone. One night, Patrick's prowess came into full view when Hall of Famer Eddie Shore massaged the neck of the Rangers' Phil Watson while against the fence. Patrick intervened by dropping his gloves and, after a vigorous tilt, left Shore with a broken nose among other swollen souvenirs.
At the close of his second full season on Broadway in 1940, Patrick got his ultimate reward with a Stanley Cup victory, the last the Rangers would enjoy until 1994. With the outbreak of World War II, Patrick was one of the first NHLers to enlist in the U.S. Army just before the bombing of Pearl Harbor.
After the war, he returned to the Rangers for 24 games and found he could not regain his form, and was sent to the minors where he ended his on-ice career with the Tacoma Rockets in 1949. Patrick then placed his full-time focus on coaching, a career he'd already started with Tacoma in 1947–48. After the Rockets disbanded, he moved over to the WHL's Seattle Bombers where served as the team's manager and coach.
In 1954, he made a return to New York where he coached the Rangers for a season before becoming the club's GM, a post he held until 1964.