Midfielder Njiva Rakotoharimalala scored in the first half to earn Madagascar a home victory and clinch their historical qualification for the 2019 Africa Cup of Nations.
The Indian Ocean Islanders also became the first team to qualify for the 2019 tournament apart from hosts Cameroon.
Now with 10 points on top of Group A, Madagascar are guaranteed a berth in Cameroon even if they lose their remaining two matches.
The 2-2 draw with Senegal at home last month was a statement of intent by the Malagasy who also beat Equatorial Guinea 1-0 away last Saturday.
If Senegal beat Sudan away later on Tuesday, they will join Madagascar for a spot in Cameroon and render Group A closed business, with the remaining two rounds of matches becoming dead rubbers.