 On 15 November 2013, O'Brien bagged another international brace against Faroe Islands in a high scoring 5–2 win at The Showgrounds.O'Brien has scored five times for the 21s and is two off Robbie Brady's all time goal scoring record with seven.In September 2017 he was called up to the senior Republic of Ireland squad for 2018 FIFA World Cup qualifiers against Moldova and Wales.