Ivory Coast qualify courtesy of Drogba double
Midfielder Gervinho, fresh from helping Lille win the Ligue 1 title, also scored two goals.
The Ivorians qualified with two rounds left to play, keeping up their 100 percent record in Group H and moving into an unassailable position after Burundi beat Rwanda 3-1 on Sunday.
The Ivorians swept into a 3-0 half-time lead before Benin threatened a comeback with a quick double from Stephane Sessegnon.
Drogba converted a penalty to make it 4-2 and there were two more goals in the final minutes.
Benin and Burundi are second in the group with four points each and both out of the running, along with bottom-placed Rwanda.
Botswana have already qualified along with co-hosts Equatorial Guinea and Gabon for the tournament next January and February.