Morrissey joined Blackburn Rovers' youth setup in 2008, aged 16, after playing for local side Ringmahon Rangers.
[1] Morrissey made his debut on 29 May 2010, coming on as a late substitute in a 0–1 home loss against Athlone Town for the First Division championship.
He achieved promotion to the Premier Division in 2011, appearing regularly, and was an ever-present figure for the club in the following campaigns.
[2] He made his U's debut on 3 February 2015, replacing Luke Chadwick in the 51st minute of a FA Cup 0–3 loss against Manchester United at Old Trafford.
[3] It was announced he had re-signed for home club Cork City on 10 December 2015, ahead of the 2016 season.