The openning goal was at the 66th minute by Yaya Banana scoring for the Indomitable Lions, heading low into the net from Karl Toko Ekambi’s cross.
Despite that Cameroon’s tournament preparations were disrupted by a row over bonuses, with the Indomitable Lions squad staging a sit-in protest before departing for Egypt.
Christian Bassogog twice failed to hit the target from good positions, while Fulham midfielder Andre-Frank Zambo Anguissa sidefooted wide from Bassogog’s pass.
Full-back Joyskim Dawa Tchakonte and captain Eric Maxim Choupo-Moting both forced fine saves out of Guinea-Bissau goalkeeper Jonas Mendes, before quick-fire goals from Banana and Bahoken secured the win.
The champions in 2017 after several big-name players missed the tournament, Cameroon have been bolstered by the return of Ajax’s Andre Onana and Paris St-Germain’s Eric Maxim Choupo-Moting – but opponents will have noticed some defensive lapses which Guinea-Bissau failed to exploit.
Cameroon are next in action against fellow tournament favourites Ghana on Saturday (18:00 BST), while Guinea-Bissau take on Benin later that day (21:00 BST).