He plays primarily as a Defender. His preferred foot is Right. His current market value is estimated at 250K €.

His most recent move was a Free from Ascoli to AC Milan U20 on 2025-08-12. The reported fee was 0.5M €.

Throughout the Italian Campionato Primavera 1 2025-2026, Mattia Piermarini featured in 3 matches, averaging 0 tackles, 0 interceptions, and 0 clearances per game, while blocking 0 shots per game.