Aston Villa
In March 2022, after ten years with Derby County, he joined the academy of Premier League side Aston Villa, with the club reportedly paying £600,000 in compensation.[6] He signed his first professional contract in September of the same year, having already featured for the under-21 side in the EFL Trophy, with academy manager Mark Harrison stating that the club were "delighted" that he had signed, and that they were "very pleased with his development so far".[7][8]
The following year, he was nominated for the Premier League 2's Player of the Month award for February, following stellar performances for Aston Villa's youth team.[9] He scored Aston Villa's only goal in a 3–1 friendly loss to Bristol Rovers on 24 March 2023,[8][10] before helping Aston Villa to the 2023 HKFC International Soccer Sevens title, scoring twice in a 3–0 win in the final against Tai Po and being named Player of the Tournament.[11]
Kellyman was named as part of the Aston Villa senior squad's pre-season squad, including a tour of the USA, in July 2023 and played in their Premier League Summer Series match against Newcastle United. Having started the match on the bench he was brought on in the second half; his shot hitting the post and rebounding resulted in a tap-in goal for Emi Buendía.[12]
On 31 August 2023, Kellyman made his professional debut in a 3–0 UEFA Europa Conference League victory over Hibernian, providing an assist for Leon Bailey's goal.[13] On 25 October 2023, Kellyman signed a new "long-term" contract at Aston Villa.[14] On 7 November 2023, Kellyman suffered a hamstring injury whilst playing for Aston Villa U21s in the EFL Trophy against Crawley Town, which was estimated to sideline him until the new year.[15]
On 3 April 2024, Kellyman made his Premier League debut, in a 4–1 away defeat to Manchester City.[16]