Aston was a forward who rose through the Manchester United youth system. His debut for the club came in 1965 against Leicester City. He went on to help the club win the 1967 League championship as well as the 1968 European Cup, where he provided a man of the match performance in the final against Benfica at Wembley Stadium on 29 May 1968. Aston scored 27 goals in 187 appearances before leaving the club in 1972 for Luton Town, later playing for Mansfield Town and Blackburn Rovers.