*Club domestic league appearances and goals, correct as of 19:00, 26 April 2024 (UTC) ‡ National team caps and goals, correct as of 00:07, 6 June 2023 (UTC)[4]
Coulson made five appearances for Middlesbrough in the 2015–16 UEFA Youth League,[5]
before signing his first professional contract with the club on 1 July 2016.[3]
St Mirren (loan)
On 9 July 2018, Coulson joined newly promoted Scottish Premiership side St Mirren on a season-long loan.[6] He made his debut soon after, on 13 July, starting in a goalless draw with Kilmarnock at Rugby Park in the Scottish League Cup. The club eventually emerged as 3–2 winners in the penalty shootout, with Coulson scoring one of their penalties.[7] He went on to score his first goal for the club on 28 July 2018, in the first minute against Dumbarton in a 6–0 League Cup win.[8] Coulson returned to Middlesbrough on 17 October 2018 after his loan was cut short, having made 11 appearances for the side in all competitions, scoring once.[9][10]
Following his return from his loan at Cambridge, Coulson broke into the Middlesbrough squad for the 2019–20 season. He made his league debut for the club on the opening day of the season in a 3–3 away draw with Luton Town.[12] On 1 February 2020, Coulson scored a first league goal of his career, equalising fifteen minutes from time in a 1–1 draw with Blackburn Rovers.[13] Coulson appeared 29 times in the EFL Championship season, including six times after the return following a break on account of the COVID-19 pandemic.[14]
Ipswich Town (loan)
Coulson joined League One side Ipswich Town on loan on 9 August 2021.[15] On 31 January 2022, Coulson was recalled by Middlesbrough having made six appearances for the club.[16]