The youngster from the Ivory Coast scored twice in the second half, including the goal of the game rifled into the top corner to make it 3-0 in the 57th minute.
John Bostock fired the team into an early lead in the fifth minute and we dominated possession throughout, but the home side also carved out chances in an entertaining encounter.
The team were quickly into their stride and took the lead after five minutes.
Ryan Mason's pass from just inside the half split open the home defence and found Bostock's run. The midfielder controlled and in an instant, rattled home a left-foot drive from 18 yards.
We held onto possession for long spells but that control was punctured by a couple of Northampton chances midway through the half.
Ishmel Demontagnac's effort was always curling away, but brushed the side-netting on the way, Jordan Archer got down well to touch wide Adebayo Akinfenwa's close-range poke and Anthony Charles glanced Ishmel Demontagnac's corner onto the roof of the net.
At the other end, Ryan Fredericks swapped wings to great effect, first cutting inside John Johnson and forcing a fine block from Kelvin Langmead on the half-hour and five minutes later, opening it up for Bostock to fire straight at Dean Snedker in the Northampton goal.
The half ended with Archer at full stretch to pluck Chris Hackett's free-kick out of the air.
The game followed a similar patter in the second half as we dictated the tempo with our passing game, but Northampton still created chances.
Archer produced a fine reaction save to tip over from Alex Nicholls five minutes into the half before a quickfire double from Coulibaly put us out of reach.
The diminuative striker's first and our second came via a poor backpass from Nicholls and Coulibaly composed himself well centrally before slotting into the corner.
He soon made it 3-0 with an excellent goal. Picking the ball up midway in the Northampton half, Coulibaly played wide to Fredericks on the left and then spun away from his marker, bursting into space to receive a return pass from Fredericks and then hammered the ball into the top corner from the edge of the box.
To their credit, despite chasing shadows for long periods, Northampton continued to chip away and created five more half-chances before finally converting in the last minute.
Hackett drilled just wide, Louis Moult shot straight at Archer, who then tipped wide from Hackett after the midfielder beat the offside trap.
Hackett delivered a free-kick headed over by Charles before repeating the trick in the 90th minute - this time Langmead met the inswinger and planted his header home for a deserved consolation.
Northampton Town (4-2-3-1): Snedker; Johnson, Langmead, Charles, Widdowson; Guttridge, Hackett; Nicholls, Harding (Tozer, 67), Demontagnac (Hoult, 67); Akinfenwa (Wilson, 84).
Spurs XI (4-2-3-1): Archer; Smith, Ekong, Hall, Stewart; Bostock (Gomelt, 75), Parrett (Gaulifuoco, 75); Fredericks (Pritchard, 63), Mason, Ceballos (Munns, 63); Coulibaly (Barthram, 75).
Goals: Northampton - Langmead (90); Spurs - Bostock (5), Coulibaly (51, 57).
Referee: Mr I Rathbone.