The penalty came as both sides were just finding their rhythm in the opening exchanges, Chato the culprit with a handball. Ebere saw his low effort saved brilliantly by Diarra, the No17's follow up header hit the bar before a third bite of the cherry was blocked by the Malian defence.
Both sides had chances in a tense opening period, with Golden Eaglets skipper Kelechi Nwakali hitting just wide and Boubacar Traore seeing his glancing header tipped over by Akpan Udoh.
The second half saw the game burst into life, with Emmanuel Amuneke's words clearly working their magic on the Nigerian youngsters. Osimhen shrugged off the challenge of Mamadou Fofana before hitting a wonderful dipping half volley towards goal, which Diarra spectacularly saved. Udochukwu Anumudu then smashed a thunderous effort at goal, which rebounded back off the crossbar and was cleared away.
Mali did not heed those warnings. Good approach play by substitute Chinedu Madueke saw him tee up Osimhen for his record-breaking goal, seeing him surpass the nine goals scored by Florent Sinama Pongolle in 2001 and Souleymane Coulibaly ten years later.
The holders doubled their advantage mere minutes later, with Bamgboye bursting down the Nigerian left before smashing a powerful effort at goal, Diarra standing little chance.
Despite a couple of late chances for Mali, from corner kicks, Nigeria retained possession for large spells and saw the game out to retain their crown. The jubilant scenes on the final whistle in Vina Del Mar will surely live long in the memories of these Nigerian heroes of the present, some of whom may just become the stars of the future.