[5] On 15 April 2017, he scored his first senior goal, the fourth in a 4–2 win over Inverness Caledonian Thistle, picking up the man of the match award at the same time.

[9] In May 2021 the Motherwell manager Graham Alexander said that Campbell would leave the club at the end of the season, as a final effort to negotiate a new contract had failed.

[10][11] On 15 June 2021, Luton Town announced the signing of Campbell after agreeing an undisclosed fee with Motherwell to secure his signature before his contract expired.

[15] On 30 January 2025, Campbell made the permeant move back to Scotland with Scottish Premiership side, Dundee United signing a short-term deal.

[16][17] In September 2017, Campbell was named in the Scotland under-21 squad for the first time ahead of the European Under-21 Championship qualifying matches against England and Latvia.