The 2019 O'Byrne Cup was played by county teams of Leinster GAA in December 2018 and January 2019.
[2] Several new rules are being trialled in the competition: It was won by Westmeath.
[5] One team (Dublin) received a bye to the semi-finals.
The three group winners advanced to the semi-finals.
The three group winners plus the team given a bye (Dublin) compete in the semi-finals.