Meanwhile, Chelsea striker Salomon Kalou, called-up to bolster Côte d'Ivoire, scored the last goal in a convincing 4-1 win for the over second placed Zambia gave them a first ever trip to the Men's Olympic Football Tournament.
The result in Abidjan proved a historic breakthrough for the Ivorians, confirming their growing international standing.
French-based striker Gervais Yao Kouassi grabbed two goals and Sekou Cisse, who is on the books of Roda JC Kerkrade in the Netherlands, netted the other to ensure top place in Group B.
Lions find their roar
Cameroon, gold medal winners in Sydney in 2000, had a slender one point advantage over Morocco before the weekend's penultimate round of qualifiers, but now find themselves with an insurmountable lead at the section's summit.
OSC Lille's Henry Elong Ewane opened the scoring after just 13 minutes but Guinea were back on level terms level 11 minutes later. However, Cameroon's 'Lions Espoir' were back in the lead in the 38th minute with a goal from Alexis Enam Mendomo.
He set up a third goal for Christian Bekamenga in the second half and qualification was assured when the news came through of Morocco's 2-0 in Gaborone.
"We attacked as much as possible but still remained vigilant in defence," explained victorious Cameroon coach Martin Ndtoungou Mpile. "It was essential was to qualify and we have achieved that. We played a good game but it was not perfect," added the Cameroon coach.
Also celebrating was French coach Gerard Gili, once at the helm of Marseille, who has led the Ivorians to China next year.
"I am very satisfied because we have achieved our objective, it's the result of long, hard work. All the players stayed with the project and now they have borne the fruit," said Gili after the one-sided win at the Felix Houphouet-Boigny stadium.
Kouassi put the Ivorians in front in the 32nd minute and then added his second five minutes later, Cisse made it 3-0 just before the hour mark before Given Singuluma reduced the deficit with 20 minutes remaining.
Kalou, playing his first game for the U-23 side, put the seal on a satisfying Sunday afternoon with the fourth goal in the 78th minute.
Yacouba Diarra netted the only goal of the game for Mali's first win of the group campaign.
Nigeria have one match left in March at home to South Africa where they will be heavily fancied to get the three points they need to again make a trip to the Olympics, where they were gold medalists in Atlanta in1996.
"These boys have done it. I am overwhelmed. As usual, these players have surprised me again and showed that they can withstand any pressure," said a smiling Siasia after the draw.