expected, missed the 2013–14 pre-season training due to his injury, but was on course to return in the autumn. On 15 August 2014, O'Brien signed for Scottish Premiership club Motherwell on loan until January 2015. He made his debut on 30 August in Motherwell's 1–0 defeat to St Johnstone. On 5 January 2015, O'Brien's loan was extended until the end of the season. He played a total of 21 games for Motherwell over the course of 2014–15. In May 2015, Derby announced that O'Brien's contract would not be renewed. Luton Town O'Brien signed for League Two club Luton Town on 9 July 2015 on a two-year contract. He made his debut for the club in a 3–1 win at home to newly promoted Championship club Bristol City in the League Cup first round on 11 August. O'Brien made eight further appearances for Luton, before joining Southport of the National League on 4 March 2016 on a one-month loan. He made his debut the following day in a 1–0 home defeat to F.C. Halifax Town. O'Brien scored his first goal for Southport a week later, scoring their third goal in a 3–3 home draw with Welling United. He made the last appearance of his loan spell on 2 April in a 2–2 draw at home to Woking. The following day, O'Brien returned to Luton after his loan expired. He was transfer-listed by Luton at the end of the season. O'Brien returned to Southport on 9 September 2016 on a three-month loan. He made his second debut for the club a day later in a 1–1 away draw with Eastleigh. However, his loan spell was cut short due to a knee injury and he returned to Luton for treatment. Newport County On 6 January 2017, O'Brien signed for League Two club Newport County on a contract until the end of the 2016–17 season, after his Luton contract was terminated by mutual consent earlier that day. He was named in the starting lineup a day later away to Stevenage, making his debut in a 3–1 defeat. His first goal was an 89th-minute winner in a 2–1 victory at home to Notts County, which ensured Newport's survival in League Two on the final day of the season. O'Brien finished the season with 20 appearances for Newport, and signed a new two-year contract with the club in May 2017. He started in the 2019 League