[5] He spent the first half of the 2014–15 season on loan at Hyde United, debuting for the club in a defeat to Hednesford Town.
[6] In the latter half of 2016, O'Brien played in the Premier League 2 as part of Manchester City's squad and was also selected by manager Pep Guardiola to travel with the first team on a number of occasions including as a backup keeper against Celtic in the Champions League.
[8] He became a regular starter for the club, keeping a clean sheet on his debut against Dundee and playing in the final of the Scottish Challenge Cup.
[13] O'Brien played in two matches of the Wales U19 team's attempt to qualify for the 2014 UEFA European Under-19 Championship in 2013 and 2014.
[1] By 2015, O'Brien had moved up to the Wales U21 squad, playing for them in eight games of their campaign to qualify for the 2017 UEFA European Under-21 Championship.