Arnau Comas was born in Cassà de la Selva, and joined Barça in 2010 from Girona. He played in the Under-12 C team under coach Jordi Font, going on to make his way up through every team at the club. He was chosen as the Player of the Tournament in the MIC, and has become a centra back with Barça DNA: Excellent bringing the ball out tall, fast and a leader.
He won the national league and UEFA Youth League with the Under-19s A in 2017/18, but in 2018/19 would suffer a series of injuries that meant he made just six appearances -all as a starter- in the UEFA Youth League. Comas spent 2019/20 on loan to Olot, for whom he was a key piece of the defence there, and is reunited with coach Garcia Pimienta this term for the Barça B team upon his return.