Appleton began his career as a youngster with his hometown club of Scarborough before joining Leicester City in March 1954, just days after his 18th birthday, after being recommended to manager Norman Bullock by then Scarborough manager and former Leicester player Reg Halton.
Under Gillies, Appleton made the number 6 shirt his own and forged a fearsome half-back line partnership with Frank McLintock and Ian King.
[2] He helped Leicester reach the 1961 FA Cup Final against Tottenham Hotspur, managed by fellow 'Scarborian' Bill Nicholson.
However Appleton did captain Leicester to their first ever major trophy, winning the 1964 League Cup and also scored in the first leg of the 1965 League Cup final, as they reached the competition's final for the second consecutive season, however he could not prevent his team losing to Chelsea, going down 3–2 on aggregate.
Appleton helped guide Scarborough to victory in the FA Trophy, including scoring the winning goal in the semi-final to see the club reach the final, also being named the club's player of the season in what would turn out to be his final as a player.