Harrington began refereeing in the Teesside Junior Football Alliance aged 14, after completing a refereeing course whilst at English Martyrs School and Sixth Form College[2] as part of The Duke of Edinburgh's Award.[3] After four years as an EFL assistant referee and four years as a National League referee, Harrington was appointed to the EFL Referees List at the start of the 2012–13 season.[4] Harrington was promoted to a Select Group 2 referee in 2016.[5] On 22 May 2021, Harrington refereed the 2021 FA Trophy Final at Wembley Stadium. Only eight days later, Harrington was back at Wembley when he officiated the 2021 EFL League One play-off Final between Blackpool and Lincoln City. After becoming a Select Group 1 referee in June 2021, Harrington officiated his first Premier League game on 16 December 2021.[6] On 29 May 2023, he was the man in charge of VAR for the EFL league 1 play-off final between Barnsley and Sheffield Wednesday. Not one to miss a chance to give his beloved Wednesday the edge, he dismissed a clear and obvious penalty.
