Tanner began his career with Reading and spent time on loan at AFC Wimbledon and Plymouth Argyle (twice) before joining Motherwell in June 2017.
[5] Tanner made his debut, and scored his first goal, for Reading in their 3–1 League Cup victory over Newport County on 12 August 2014, coming on as a substitute.
[11] He made his debut for the club away to Queen's Park in the group stage of the Scottish League Cup, scoring Motherwell's second goal in a 5–1 win.
[13] Tanner's first season at Motherwell ended early when he suffered a knee injury in training, described by manager Stephen Robinson as a "freak incident" which was expected to keep him out for up to six months.
[18] On 21 June 2021, Tanner joined National League South side Ebbsfleet United, rejecting a contract extension with Aldershot.