Auchendinny, near Penicuik, Midlothian born right back George Affleck began his football career with Penicuik before he was discovered by Second Division Leeds City, who signed him in June 1909, making his Football League debut against Burnley that November. From his debut onwards he was a first team regular and missed only one match per season in 1910-11 and 1911-12, being ever present in 1913-14 as Leeds finished fourth in the Second Division.
Affleck had scored his only career goal, a penalty in a 5-1 win over Preston North End in February 1913, and was a regular until the suspension of football due to the onset of the First World War in the summer of 1915. He played 36 matches for Leeds City in wartime league football during 1915-16, and after the conflict he returned to Elland Road and played twice for Leeds City in the 1919-20 season before they were expelled from the League for financial irregularities. On 17th October 1919, an auction was held at the Metropole Hotel in Leeds, where the playing staff was auctioned off along with other assets of the club, Affleck being sold to Second Division club Grimsby Town for £500 after 191 appearances for Leeds City.
He played 18 times for Grimsby during the 1919-20 season, at the end of which they were relegated, and he then spent a further five seasons as a regular in The Mariners’ line up in the Third Division, before his retirement in the summer of 1925 after 210 appearances for Grimsby.