Nigeria's goal came from a penalty after Anam Imo was fouled in the box in the 36th minute of the encounter.
Nigeria were beaten 1-0 in their first game by Germany but bounced back to take all three points from Haiti on Thursday, August 9.
Nigeria’s U20 girls, needed a win to keep hope alive and it was stand-in captain Rasheedat Ajibade that scored the only goal of the game to give the Falconets the win.
The goal came from a penalty after Anam Imo was fouled in the box in the 36th minute of the encounter.
In the second half, the Falconets held on to their lead after the Haitians improved in search of an equaliser.
Chiamaka Nnadozie won Woman of the Match after her impressive saves between the goal for Nigeria.
Nigeria are now second in Group D and will aim to beat China in their next game to seal qualification to the quarter-finals.
China were beaten 2-0 by China in the other Group D game.