Franco Mastantuono is an Argentine professional footballer who plays as a midfielder for Argentine Primera División club River Plate.

Born in Azul in the Buenos Aires Province of Argentina, Mastantuono also took an interest in tennis as a child, and was a national-level youth player.

Mastantuono began his footballing career at the age of three, playing for River de Azul, where his father was the coach. In 2017, while playing for River de Azul, he was invited to trial with professional side River Plate, but despite being offered a place in the academy, he declined, as his family wanted him to continue pursuing a career in tennis. Instead, he signed for Club Cemento at the age of eleven.

Born in Argentina, Mastantuono is of Italian descent and holds dual Argentine-Italian citizenship. He was first called up to the Argentina national under-17 team squad by manager Pablo Aimar while still only fifteen. His impressive performances with the River Plate youth teams caught the attention of Argentina national under-20 team coach Javier Mascherano, who called him up to train with the team in mid-2022.