Formerly with Dumbarton and Cardiff City, outside-left John McMillan made around twenty league appearances during his two-season stay at Exeter City in the early 1960s. He left to play for Barry Town. 

Having played for Vale of Leven Academy Former Pupils in the 1956 Scottish Amateur Cup, John joined Dumbarton as an amateur whilst continuing an engineering apprenticeship. Making appearances for Scotland in amateur internationals, he eventually turned professional with Cardiff City in 1959.

Playing only a couple of league games for his new club, John signed for Exeter City for a fee of £1500 in October 1961 and soon made his debut against Oldham Athletic. Losing his place after just four games, he made just four more appearances that season. 

After a single appearance early the next season, most of his twelve league games in 1962/63 came in March and April during the backlog caused by that winter’s severe weather. Making his final appearance against Gillingham in April, John moved back to South Wales to play for Barry Town and Merthyr Tydfil before playing in the Welsh League.