Brennan Dickenson signed for Exeter City early in 2020 on a short-term deal to the end of the season. He was to play thirteen times for City including three play-off substitute appearances.    

Brennan was at Southampton before joining Dorchester Town as an eighteen-year-old. After a year at Dorchester Brennan transferred to Brighton & Hove Albion in January 2012. He failed to play for Brighton’s first-team and -  after loan spells with Chesterfield, AFC Wimbledon and Northampton - agreed terms with Gillingham in 2014. Making around seventy league appearances in Kent, he moved to Colchester United in 2016 where he made eighty-five league appearances before leaving for MK Dons in July 2019.

It was after starting just two league matches for MK Dons that Brennan arrived at St James Park in January 2020. He made his debut for Exeter City on 19 January 2020 at Grimsby and, by the end of the curtailed 2019/20 season, had played 10 league games scoring twice. When the season resumed for the play-offs he came on as a substitute in each of City’s three games before his release in July 2020.

He signed for Carlisle United on a two-year deal in August 2020 where he played more regularly in his second season before signing a new contract in the summer of 2022. Brennan then suffered a cruciate knee ligament injury and, after not playing at all during 2022/23, was released at the end of the campaign ahead of agreeing a one-year deal with National League Oldham Athletic in August 2023. Then, after appearing in little more than half of Oldham's league fixtures, he switched to Hartlepool United in February 2024 on a loan deal through until the end of the season ahead of his eventual release by Oldham.  

Having established connections in the Carlisle area, Brennan joined nearby Queen of the South in June 2024.