Cotter was born in Mackay, Queensland, Australia, and is of German Jewish and Torres Strait Islander descent.

[8] In 2016, Cotter joined the North Queensland Cowboys under-20 side, playing just two games before tearing his anterior cruciate ligament (ACL), ruling him out for the season.

[14] Cotter started the 2019 season playing for the Cowboys' Queensland Cup affiliate, the Mackay Cutters, where he scored nine tries in 15 games.

[21] In June, Cotter was selected for game one of the 2022 State of Origin series which Queensland won 16-10 at Stadium Australia.

Cotter played 18 matches for North Queensland in the 2022 NRL season as the club finished third on the table and qualified for the finals.

[22] In October, he was named in the Australia squad for the 2021 Rugby League World Cup[23] and played two games in the tournament.

[25] Cotter was named in the front row for Queensland ahead of game one in the 2024 State of Origin series.