Kelly started playing rugby at under six years old for Rochdale RUFC, in Greater Manchester.

[5] Due to a number of other players considered more talented he was not offered a professional contract at 18 so joined Loughborough University.

[6] On 10 April 2020 Kelly signed for Leicester Tigers, joining for the end of the delayed 2019-20 Premiership Rugby season.

[8] He quickly became a regular starter at inside centre, and by April 2022 was being highlighted by team mates as a defence leader as Leicester prepared for a European Rugby Champions Cup round of 16 tie with Clermont Auvergne.

[9] In February 2025, he signed a two-year contract with Munster in the United Rugby Championship ahead of the following season.