Adian Manning joined Watford in 2012 and progressed through to their Under-18s and Under-23s squads. In an interview with Watford, he described himself as a "a box-to-box midfielder. I can play in a deeper role, but I can also move into an attacking position and be creative. I can play anywhere in the midfield. I look up to Moussa Sissoko, Sergio Busquets and Luka Modrić."

Towards the end of the 2022/23 season he joined Norwich on trial playing for the Under-21s against Southampton on 23rd April 2023.

He then signed for Norwich on 4th July 2023, playing that evening in a pre-season friendly for Norwich against Barnet.

On 2nd January 2023 Adian signed a new contract to stay with the Canaries until June 2025 with the Canaries holding an option to extend by a further year. He had been a regular member of Alan Neilson's under-21 squad, netting four goals in nine matches in the Premier League 2 Division 2.