He turned professional in October 1960 and made his first-team debut on 4 November 1961, at home to Bristol Rovers in place of the injured Terry Paine.
His six years at the Dell were spent in the shadow of Paine and John Sydenham and as a result he only made 25 league appearances for The Saints, in which he scored once.
He spent the 1976 season with the newly formed American Soccer League side Tacoma Tides where he served as a player and assistant coach.
On a minor note, Chadwick coached Bruce Arena, the future manager of the United States men's national soccer team, who was a Tides back up goalkeeper.
After a successful season with what started as a scratch side, Chadwick returned to the NASL as head coach of Fort Lauderdale Strikers in 1983, signing with the team in September.