Mikel John Obi and Ayegbeni Yakubu were on target as Nigeria set up an African Nations Cup quarter-final with hosts Ghana with a 2-0 win over Benin in their final group game.
Ivory Coast's 3-0 triumph over Mali in the night's other Group B encounter ensured the Super Eagles a berth in the last eight.
Coming into the final round of fixtures, Nigeria needed to win and hope tournament favourites Ivory Coast beat Mali, while also recovering a goal-difference deficit of two.
The Super Eagles went ahead when the Benin goalkeeper parried Taye Taiwo's long-range free-kick. Peter Odemwingie latched onto the loose ball and lofted it back into the area for Chelsea midfielder Mikel to nod home Nigeria's first goal at this year's tournament.
Mikel helped put the game to bed after 86 minutes, splitting the Benin defence with a great through-ball and Everton striker Yakubu latched onto it to fire home.
Ivory Coast made it three wins from three to sealed their passage to the quarter-finals as group winners.
Goals from Chelsea striker Didier Drogba, Marc Zoro and Boubacar Sanogo earned the 2006 finalists a meeting with Guinea in the knockout stage.
The favourites were off to a flyer in Accra when Drogba opened the scoring in the ninth minute after latching onto a defence-splitting pass from Yaya Toure and firing the ball home from the left side of the penalty area.
Zoro doubled his side's lead when he rose highest from a Koffi N'Dri corner after 55 minutes.
Five minutes from the end, Sanogo had a simple tap-in after Toure's powerful 25-yard shot from the right was only parried, and the Ivorians eased to victory.
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