Senegal dominated proceedings at the Stade Leopold Sader Senghor Stadium in Dakar as they grabbed the lead through Ibrahima Diedhiou in as early as the eighth minute.
The Tunisians surged forward in trying to get the equaliser but failed to find the back of the back of the net as the scoreline remianed unchanged at half-time.
Despite pushing the hosts on the backfoot for much of the second half, it was Senegal who scored and sealed off the victory through Mouhamadou Diallo in the 84th minute.
The win sees the Cubs of Teranga go top of the group with six points from two games, and leaves South Africa and Tunisia to battle it out for the second semi-final spot in the group on Friday.
Senegal next face bottom of the group Zambia, and will look to kill off their opponents as a confidence booster ahead of the semi-final round next week.
Group standings:
Team P W D L GD Pts
Senegal 2 2 0 0 +4 6
South Africa 2 1 0 1 -1 3
Tunisia 2 1 0 1 -1 3
Zambia 2 0 0 2 -2 0