Comer is a former pupil of
St Jarlath's College in
Tuam, and also a graduate of
NUI Galway, with whom he reached the 2018
Sigerson Cup final. Comer did not play for Galway at
minor level. He was a member of the Galway team that won the
All-Ireland Under-21 Football Championship in 2013. He made his senior championship debut when he came on as a substitute against
London in the
2014 Connacht SFC. Comer was part of the Galway team that won the
2016 Connacht SFC. He started all of the team's games as the county won its first Connacht SFC title since 2008. Comer was introduced as a late substitute in Galway's
2025 Connacht SFC semi-final victory against Roscommon. He sustained an injury before the Connacht SFC final and did not feature in the matchday 26 until just before the second round robin game against Derry. ==Personal life==