Sheffield United Kelly came through the
Academy at
Sheffield United to make his senior debut for the "Blades" as a late
substitute for
Matt Done in a 3–1 defeat to
Coventry City at the
Ricoh Arena on 30 April 2016. He joined
Stalybridge Celtic of the
National League North on
loan in August 2016. He made ten appearances for the "Celts" over a five-week stay at
Bower Fold.
Port Vale Kelly signed a one-year
contract, with the option for a second year, at newly
relegated EFL League Two club
Port Vale in June 2017. He said he was looking forward to working with
manager Michael Brown and being reunited with former Sheffield United
coach Chris Morgan. On 8 September 2017, he joined National League North side
Bradford Park Avenue on a one-month loan after manager
Mark Bower needed cover for the injured
Shane Killock,
Matt Hill and Luca Havern. He scored his first goal in senior football in his final appearance for Avenue, after combining well with
Oli Johnson in a 2–0 win over
Brackley Town at the
Horsfall Stadium. On 26 January 2018, he joined
Kevin Davies's National League North side
Southport on loan until the end of the
2017–18 season. He recovered from a car accident on the
M6 motorway to make a total of 11 appearances for the "Sandgrounders". Upon his return to
Vale Park he was informed by manager
Neil Aspin that he would not be retained beyond the summer.
Larne On 2 August 2018, Kelly joined
NIFL Championship side
Larne. He established himself in the side as a left-sided centre-back in the club's favoured three at the back
formation, as Larne went on to win the
2018–19 NIFL Championship. He made 27 appearances before the
2019–20 season was ended early due to the
COVID-19 pandemic in Northern Ireland. On 2 December 2020, he played in the
County Antrim Shield as Larne held
Glentoran to a 0–0 draw and then won the resulting
penalty shoot-out 4–3 to win the club its first major trophy in 33 years. He scored his first goal for the club on 11 December, "a stunning curler into the top corner" in a 3–1 win over
Linfield at
Inver Park. He made 20 appearances in the
2020–21 campaign, helping Larne to finish in a
UEFA Europa Conference League qualification place. Larne retained their County Antrim Shield title with a 1–0 win over
Linfield. He played 30 games in the
2021–22 season, including the 4–2 win over Glentoran at
The Oval in the final of the
UEFA Europa Conference League play-offs. A third-successive County Antrim Shield title was secured with a penalty shoot-out victory over Linfield. Larne won the first Irish League title of their 134-year history in the
2022–23 season. He left the club at the expiry of his contract to find first-team football elsewhere.
Coleraine Kelly signed a three-year deal with
Coleraine on 14 June 2023. On 7 November, he took
penalties in a 44 kick long
penalty shoot-out with
Ballymena United, which Coleraine won 18–17. He played 33 games in the
2023–24 season. He missed most of the
2024–25 season with a long-term injury. He did not feature in the
2025–26 season. ==International career==