Ngozi Okobi opened the scoring on the quarter-hour mark, while Desire Oparanozie extended the advantage midway through the second period.
The Nigerians, backed by a buoyant and colourful band of supporters, went ahead following smart work from Francisca Ordega on the right side of the box, with the midfielder playing a perfect low ball across the face of goal for Okobi to score.
With Okobi, Ordega and Oparanozie all dangerous in possession, Nigeria provided a regular threat, although Korea Republic, with their short-passing game in evidence, provided a tough opponent for the 2010 runners-up.
However, Korea Republic suffered a massive blow in the latter stages of the first half with midfield schemer Yeo Minji, the 2010 FIFA U-17 Womenâ€™s World Cup adidas Golden Ball winner, forced off with injury.
Nigeria claimed a deserved second with Ebere Orjiâ€™s cross into the penalty finding Oparanozie who scored with a stylish header.
Late chances went the way of Esther Sunday but Nigeria had to make do with a 2-0 scoreline.
â€śThis was the planned result,â€ť said Nigeria coach Okon Edwin. â€śWeâ€™ve even improved compared to last World Cup and weâ€™ll try to do better than that, which means that we want to do better than second place.”