Alex Campbell started with local junior club Inverness Clachnacuddin.

In August 1906, he was given an opportunity with Middlesbrough, then in the English First Division. Campbell spent five years with the Ayresome Park club, mostly in the reserves after a lengthy run at left-back in the first-team in his debut season.

A broken leg had disrupted his chances in the North East and he was happy to sign for Leeds City in December 1911 with the prospect of first-team football. After a decent display in a Midland League game that month he was drafted into the City side for his debut against Nottingham Forest on 30 December, replacing Alec Creighton at left-back. Unfortunately, he sprained a knee after twenty minutes and had to limp off. He returned to the action after ten minutes, but his knee gave way again and he had to retire.

That was the end of Campbell's City career and he returned to Scotland, signing for Inverness Clachnacuddin in September 1912.