Forward Kamilou struck in the 90th minute at the Stade Felix Houphouet-Boigny in Abidjan to complete a fine comeback from the Cameroonian outfit.
The victory moves Cotonsport to the top of Group A on four points, two ahead of Real Bamako and ASEC.
Kamilou put the visitors ahead after 21 minutes, only for Ivorian outfit ASEC to level through midfielder Hugues Zagbayou 13 minutes later.
And the hosts then went ahead in first-half injury time as attacker Ibrahima Fofana netted.
But ASEC's lead lasted just 15 minutes into the second half, Cotonsport defender Nicaise Zimbori scoring from the spot on the hour mark.
The game looked to be heading to a draw, but Kamilou had other ideas as he netted a late winner to give the visitors all three points.
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