Goalkeeper Williamson began his career with Murton Red Star and Wingate Albion in the North-East, before moving South to join Croydon Athletic in July 1913.
He won the league championship in his first season on goal average and played 126 times for the South London club before they went out of existence in 1916.In World War I, Ernie was conscripted to the Footballer's Battalion, but moved on to the RASC and became a sergeant major. While in the forces, he played twice for the Army.
It was as a war-time guest he featured for Tottenham in one game and it caused a bit of a rumpus, as he had not been granted permission to play by his club Arsenal and Tottenham received a fine of five guineas for the offence.
On leaving Croydon, he moved across South London to play for Arsenal, making his debut on the first day of the first season after the warfare had ended in the 1919-20 season. He played 105 times for the Gunners.
Played a Victory international for England against Wales in October 1919 and twice for the full national side against Sweden in May 1923.
Left Arsenal a month later for Norwich City, where he kept goal 47 times in two years and during his time at Carrow Road, he also kept wicket for the Norfolk county cricket side.
Ernie Williamson retired from playing in 1925 and went on to run a pub in Norwich and was a Norwich lawn bowls club groundsman before he died on 30th April 1964.