The McNamara family moved to Sault Ste. Marie when George was a young boy and it was there that he learned his early hockey skills. The new professional hockey scene was running at full speed when McNamara made his pro debut with the Canadian Soo of the International Hockey League in 1906-07.
He was a big, rugged defenseman and was in demand in those early years. McNamara played with four different clubs in four different leagues between 1908-09 and 1912-13. He was never a real offensive threat but did manage to score 15 goals in 16 games with the Waterloo Colts of the Ontario Professional Hockey League in 1910-11.
McNamara played with his only Stanley Cup winning team in Toronto as a member of the Blueshirts squad of 1913-14. He stayed in Toronto to play the following year with the Shamrocks and then returned to the Blueshirts before joining the Canadian Army during the World War I.
He was a member of the 228th Battalion team that participated in the National Hockey Association before having to drop out of the league when they were ordered overseas on February 10, 1917. After returning from the service, McNamara coached the Sault Ste. Marie Greyhounds to the Allan Cup in 1924.
George and his brother, Howard, were known as the "Dynamite Twins" during their playing days because of their bone-crunching body checks.
George McNamara was inducted into the Hockey Hall of Fame in 1958.