He previously played for Wolverhampton Wanderers,[1] Dunfermline Athletic, Ross County and Raith Rovers.

Armstrong began his career playing youth football with Scottish club Hamilton Academical.

[2] After primarily playing for the club's youth sides, Armstrong was loaned out to Scottish Championship side Dunfermline Athletic at end of January 2018, with the player expressing a desire to play first-team football.

[1] Armstrong then signed a short-term contract with Raith Rovers, and scored five goals in 11 appearances for the Kirkcaldy club.

[6] He scored on his debut for Ross County against East Fife in the Scottish Challenge Cup.