On 16th June 2023 Norwich City signed 19 year old wide player Kellen Fisher from Conference side Bromley, for an undisclosed fee. The initial plan was that he would be with Norwich's academy sides but an impressive pre-season saw him named on the bench for Norwich's opening day clash with Hull on 5th August 2023. He made his Norwich debut playing all 90 minutes of the 1-0 Carabao Cup win at QPR on 16th August 2023, providing the cross for Jon Rowe to score the 90th minute winner.

Kellen had progressed through the academy at Bromley, making his debut for the club in the FA Trophy against Dover Athletic in December 2021.

After a loan spell at Welling United, Fisher returned to Hayes Lane and went on to feature 27 times in the National League during the 2022/23 season, including two fixtures in the National League play-offs.

Fisher was later named as the Non-League Paper's Young Player of the Year, as well as Bromley's Supporters' Player of the Season for the 2022/23 season.

Fisher made a total of 14 appearances in 2023/24 as Norwich finished sixth reaching the Championship play-offs, before losing 4-0 to Leeds.

On 24th May 2024, Fisher was called up to the England Men's Elite Squad (formerly known as the Under-20s) for friendlies with Sweden and the Republic of Ireland in June 2024. Teammates Abu Kamara and Brad Hills were also called up as was former Canary Alex Matos. He started for England Under-20s as they beat Sweden 2-1 on 7th June. Fisher played 66 minutes before being replaced by Roman Dixon