He currently plays for Milan Futuro, wearing the number 20 shirt. At the international level, he represents Italy U19. He plays primarily as a Forward. His current market value is estimated at 400K €.

His most recent move was a from AC Milan U19 to Milan Futuro on 2025-01-01.

In the Spanish Segunda Division 2025-2026 season, Diego Sia scored 0 goals and provided 0 assists across 4 appearances, averaging 0 goals per game with 0 shots attempted and 0 on target.