in Russia after beating Zambia.
The Eagles secured the qualification on Saturday evening with a game to spare in Group B with Alex Iwobi's lone goal in the 74th minute.
Gernot Rohr's men humbled their Zambian visitors at the Godswill Akpabio Stadium in Uyo, the Akwa Ibom State capital, following an impressive performance against Cameroon.
Substitute Iwobi blasted home from a pullback by Shehu Abdullahi 17 minutes from time to secure qualification.
In a high tempo first half, Zambia thought they had taken the lead when Augustin Mulenga bundled home but his 23rd-minute effort was disallowed for offside.
In the 36th minute, Zambia striker Alex Ngonga, whose pace troubled the Nigeria defence throughout, forced goalkeeper Ikechukwu Ezenwa to parry the ball behind for a corner.
The Super Eagles peppered the Zambian goal with shots in the closing minutes of the first half, but skipper Mikel Obi, Odion Ighalo and Moses Simon all failed to trouble Zambian goalkeeper Kennedy Mweene.
Nigeria were the brighter of the two teams after the break as Wilfred Ndidi saw his looping header pushed away by Mweene.
The Eagles carved out the better chances, although Zambia looked dangerous on the counter-attack until Iwobi settled the affair and sent Nigeria to the World Cup finals.
With the victory, the three-time African champions are leading the group with 13 points from five games, while Zambia sit second with seven points from the same number of games.
On the other hand, Cameroon are third in the group with six points and Algeria with just one point, both from five games.
It will be Nigeria's sixth appearance at the World Cup tournament.
