Mexico opened the scoring through Kevin Magana, with stunning efforts from Kelechi Nwakali and Orji Okwonkwo seeing the African side ahead. Diego Cortes's remarkable solo effort levelled matters, before Osinachi Ebere and Victor Osimhen's late record-equalling penalty saw the Golden Eaglets into an all-African final against Mali.
Emmanuel Amuneke's side began to grow into the game, with Kelechi Nwakali hitting a low drive from the edge of the Mexican penalty area with his venomous drive stinging the palms of Romero before the ball was cleared away.
The game see-sawed back Mexico's way, with a free-kick from the Mexican left headed goalwards by Jose Esquivel. The chance forced a superb point blank stop by Akpan Udoh, onto the crossbar and eventually cleared behind.
Nigeria rode their luck, with a couple of good Mexican opportunities and after riding the storm, managed to level things up thanks to the superb technique of their captain. Nwakali lined up a free-kick from around 25 yards, and curled a perfect effort into the bottom left-hand corner. Romero stood no chance.
Amuneke's charges sensed their opponents were on the back foot, and Okwonkwo took advantage, producing one of the moments of the tournament to see his side ahead. He cut inside from the left onto his right foot and thumped an effort in off the crossbar.
After the break, Mexico took time to reassert their rhythm after the shock of going behind. Cortes then stepped up to score what must be considered one of the best goals ever scored in the Estadio Ester Roa. He picked up the ball on the Mexican right just inside the Nigerian half and proceeded to dribble past five players, showing incredible close control before slotting calmly past Udoh.
Nigeria were undeterred by Cortes's golazo and struck back. Ebere found space on the Nigerian right just inside the Mexican penalty area after a long through ball. His right-footed effort was too strong for Romero, who got a hand to the strike but could not keep it out.
John Lazarus was taken down in the Mexican penalty area, giving Osimhen the chance to score his ninth goal of Chile 2015 and go level at the top of the all-time U-17 World Cup goalscoring charts. He slotted home with ease, adding gloss to the Golden Eaglets victory.
Nigeria head to Vina Del Mar on Sunday for an all-African final against continental champions Mali while Mexico will face off against Belgium in the match for third place earlier the same day.