Ismaila Sarr put Senegal in front in the 16th minute and Habib Diallo made it 2-0 midway through the second half.
Jean-Charles Castelletto headed in to pull one back for the Indomitable Lions in the 83rd minute, but Sadio Mane sealed the win in stoppage time to hand Teranga Lions a 3-1 victory at the Stade Charles Konan Banny on Friday night.
Cameroon, five-time champions, have one point after two games and will most likely need to win their final group tie against The Gambia on Tuesday to progress to the knockout stages.
Cameroon recalled Manchester United goalkeeper Andre Onana, who missed a draw with Guinea after arriving late in Abidjan, but slack defending contributed to the goals he conceded.
Senegal kicked off with five of the team that started the 2022 final against Egypt in Yaounde, which they won in a penalty shootout with Mane scoring the decisive spot-kick.
The Indomitable Lions had to do without star forward Vincent Aboubakar again as he had not recovered from a thigh injury that ruled him out of a draw with Guinea four days ago.
Senegal could be confirmed Group C winners depending on the outcome of the Gambians and Guinea match tonight.
Onana and the Indomitable Lions will hope to register their first victory of the tournament in Ivory Coast when they take on The Gambia in the last Group C match on Tuesday.
Senegal will take on Guinea on Tuesday in their final group-stage match