Captain Chidera Harmony scored two first-half penalties. Oluebube Umejiaku added a third after the break. Oluwakemi Adegbuyi finished the scoring in the 90th minute.
Harmony converted in the 15th minute after Adegbuyi was fouled, then scored again from the spot in the 35th. Umejiaku, 16, struck from outside the box in the 67th minute. Adegbuyi, who had won both penalties, scored her fourth goal of the tournament in stoppage time.
Nigeria scored 17 goals and conceded two across the six-team competition in Côte d’Ivoire. They dethroned Ghana as regional champions.
The Flamingos now turn towards the FIFA U-17 Women’s World Cup in Morocco. Sunday’s display — two penalties, a long-range strike and a late fourth — closed a perfect regional campaign.