George Cullen, the son of a telegraph clerk, was a native of Maryhill, Glasgow. He grew up in the Partick district where he joined the local gymnastics club at a young age. In 1908, he was one of eight Scotsmen selected for the Great Britain gymnastics delegation at the 1908 Olympics in London. Participating in the team event, the British team placed eighth with 196 points. Cullen continued his involvement in gymnastics following the Olympics, also serving as a judge on multiple occasions. Cullen later served in World War I in the Black Watch (Royal Highlanders) and was killed in action at Arras in 1918. He is memorialised at the Arras Memorial at the Faubourg d’Amiens British Cemetery in France.