Bromley Born in
Bromley, Tanner played youth football for
Charlton Athletic and
Arsenal. He joined the
Bromley Academy in 2015 after being released from Arsenal. He made his league debut for Bromley on 23 November 2019 in a 2–0 win over
Sutton United. The following season, shortly after signing a first-team contract, his dual registration move to
Folkestone Invicta was announced on 9 October 2020. He made his Folkestone debut the following day in a 1–0 win over
Potters Bar Town.
Lewes Following his release from Bromley, he signed for
Lewes in the summer of 2021. After 7 goals and becoming an important part of the team, in November he extended his contract until the end of the 2022–23 season, with manager Tony Russell saying that "[Tanner] is probably the best young player I have ever worked with. And I have worked with some good ones." Amidst interest from multiple clubs, it was reported that Lewes had accepted a £100,000 bid from Premier League club
Tottenham Hotspur in January 2022. However, Tanner turned down the transfer after failing to agree personal terms, leading to him receiving death threats from Tottenham fans.
Cardiff In May 2022, it was announced that Tanner would sign for
Cardiff City on 10 June on a two-year contract, following a successful trial, for a reported fee of around £50,000. He made his Cardiff debut in the
EFL Cup on 9 August, in a 3–0 defeat to
Portsmouth. On 9 January 2023, Tanner joined
National League club
York City on loan for the remainder of the season. He made his York debut on 24 January in a 2–0 defeat to
Oldham Athletic. After impressing recently hired Cardiff manager
Erol Bulut in pre-season, he made his league debut for Cardiff on 12 August 2023, in a 2–1 defeat to
Queens Park Rangers. He scored his first professional goal on 16 September 2023 in Cardiff's 2–0 home victory against
South Wales derby rivals
Swansea City.He finished the season with 40 appearances and 2 goals, although primarily appeared as a substitute with only 9 league starts. In the
next season, Bulut told Tanner he would have to lose weight to gain a starting spot. Tanner suffered a cut on his leg after an advertising board fell on him on 25 August in a 1–1 draw against Swansea.He signed a three-year contract extension on 5 October 2024. Under new manager
Omer Riza, Tanner became an important part of the Cardiff team. After missing more than two months with a knee injury, he made his return on 29 March 2025 in a 1–1 against
Sheffield Wednesday. He finished the season with 31 appearances and 2 goals as
the Bluebirds were relegated to
League One. Two weeks later however, he collided with an advertising board during a 1–0 victory over
AFC Wimbledon, suffering damaged ankle ligaments and a small fracture in his fibula, expected to rule him out for four months. In February 2026, Tanner scored the opening goal in a 2–1 victory against Bristol City, marking his first goal in a Severnside derby." ==Career statistics==