The McLarnin family moved to Canada when Jimmy was young. Jimmy started boxing when he was ten and was discovered by Charlie “Pop” Foster who became his lifelong friend and manager.

McLarnin was honoured as Canada’s “Boxer of the Half-Century”. He was inducted into the Canadian Sports Hall of Fame and Ring’s Boxing Hall of Fame.

Jimmy fought professionally for thirteen years from 1923 to 1936 and held a record of 63 wins (20 KO, 42 decision, 1 foul), and 14 losses (3 draws, 10 decision, 1 KO). Over his career he boxed fourteen champions.

He knocked out Young Corbett III at 2:37 of the first round to take the World Welterweight title, In Los Angeles, Ca on May 29, 1933.

On May 28, 1934, he lost the title to Barney Ross in round 15 on a point decision, at Madison square Garden Bowl, NY.

On September 17 of the same year, McLarnin regained the World Welterweight title from Ross, again in round 15 on a decision at Garden Bowl, Long Island City, NY.

In one more rematch, on May 28, 1935, Ross out-pointed McLarnin again in round 15, to take the world title at the Polo Grounds, NY.