Fisher, 31, will work under Broncos head coach Tony Rea and fellow assistant Mick Howell.
Rea said: “Ben is a person who has displayed the character attributes needed to be effective as he transforms his experiences as a player into his abilities to coach. The club looks forward to him integrating into the programme.”
The Broncos have also brought in Barny Allen as Head of Strength and Conditioning from rugby union club Gloucester.
He will be assisted by Aiden Oakley and Mike Eccles.
Rea added: “Barny Allen is a strong acquisition and a statement of intent. He will be building this very important off season. He will be supported by Mike Eccles who remains as his assistant. Aiden was an intern last season who we just had to find a way to keep. He is an addition and an important one.”
Oakley is a former Harlequins Under 20s player, and is studying at Middlesex University.