[2] After progressing from the underage grades, Cotter first played at adult club level with the Blackrock intermediate team in 2019.
He won a Cork IHC medal that year before later being promoted to the club's senior team.
[3] Cotter was part of the Blackrock team that beat Glen Rovers to win the Cork PSHC title in 2020.
After claiming an All-Ireland U20HC title as a member of the extended panel in 2020, he collected a winners' medal on the field of play the following year.
[6][7] Cotter had been close to the senior team over the following few seasons before making his debut in the pre-season Munster SHL in 2024.