Raissa Feudjio bagged the spoils with an 86th minute decider at the Independence Stadium.
Both sides had chances in the opening exchanges, as Cameroon's Yango Grace volleyed just wide of the mark before Banyana's Noko Matlou thundered a shot against the upright in the 12th minute.
Vera Pauw's charges saw more of the ball as the opening stanza ended goalless.
Cameroon started to threaten in the latter stages of the tie, as Gaelle Enganamouit was narrowly off target with an acrobatic attempt on goal before Gabrielle Onguene drew a fine save from Banyana goalkeeper Roxanne Barker in the 73rd minute.
Cameroon eventually broke the deadlock with four minutes to go when Feudjio tapped into an empty net following a mistake from Barker and one of her defenders.