An outside left, Hopkin was born in Dewsbury, West Riding of Yorkshire, and began his career with Darlington. After a spell as a wartime guest with Tottenham Hotspur, Hopkin joined Manchester United in 1919. He made his debut away to Derby County on 30 August 1919, playing on the left wing in a 1–1 draw at the Baseball Ground.
Hopkin, an outside left from Dewsbury, Yorkshire, began his professional career with Darlington before joining Manchester United in 1919 after a wartime loan to Tottenham Hotspur. He made his debut for the club on August 30, 1919, playing as a left winger in a 1-1 draw against Derby County at the Baseball Ground.