On 15 July 2014, Ó Ríordáin was appointed Minister of State with responsibility for New Communities, Culture and Equality at the Department of Justice and Equality and at the Department of Arts, Heritage and the Gaeltacht. As Minister of State he prioritised reforming the direct provision system, ending the legal entitlement of Church-controlled state-funded institutions to discriminate against LGBT people, and played a key role in the Yes campaign in the 2015 Marriage Equality Referendum. He coordinated the Polska Éire 2015 festival, which was a week-long cultural and sporting festival in the run-up to the March 2015 Republic of Ireland v. Poland UEFA European Championship qualifier.