Scowen came through Wycombe Wanderers' youth system, making his professional debut on 26 March 2011, in their 3–0 away win over Morecambe in League Two.[3] He came on as substitute for Kevin Betsy in the 89th minute.[3] Wycombe striker, Scott Rendell said; "It's great to see him come out and get his chance because he will be a big player for this club if he carries on doing what he's doing."[4]
In April 2011, he was one of four Wycombe academy scholars to be awarded professional contracts by the club.[5] On 21 October 2011, he signed a three-month loan deal with Hemel Hempstead Town.[6]
Scowen was immediately recalled by Wycombe following their appointment of Gareth Ainsworth as new manager.[8]
After a strong first half to the 2014–15 season, Scowen attracted the attention of several higher-league clubs, and in January 2015, Scowen left Wycombe to join Barnsley.
On 1 July 2017, Scowen joined Championship club, Queens Park Rangers, following his decision to leave Barnsley at the end of his contract.[10]
Sunderland
In January 2020 he joined Sunderland.[11] On 8 September 2020 he scored his first goal for Sunderland in an EFL Trophy tie against Aston Villa U21s.[12] On 25 May 2021 it was announced that he would leave Sunderland at the end of the season, following the expiry of his contract.[13]
Return to Wycombe
On 29 June 2021, Scowen returned to sign for his first professional club Wycombe Wanderers on a two-year contract.
He signed a new one-year contract extension in April 2023.[14]