Campbell had his man down twice in quick succession before backing him up on the ropes and forcing the referee to step in.
Topping the bill in his hometown of Hull, Campbell found a perfectly timed right hook within moments of the first bell to put his opponent on the canvas.
Harris recovered momentarily but was dropped again shortly after following a flurry of quick hooks.
Sensing the victory, Campbell kept up the pace and landed his jab easily and constantly backed it up with powerful hooks.
After one minute and 28 seconds of the first round, with Harris on the ropes and taking a lot of punishment, the referee stopped the contest.