Making his debut as a second-rower alongside older brother Louis in September 2003, Leicester-born Deacon made a total of 135 appearances for Tigers in two spells with the club and shared in three Premiership title wins.
He was a member of the matchday squad for all three Finals in 2006/07 when Tigers lifted the Premiership and Anglo-Welsh titles and finished runners-up in Europe’s Heineken Cup.
He also made 30 appearances in two seasons with Gloucester before returning to Leicester in 2012.
After playing his early rugby with Wigston and Syston, Deacon gained England age-group honours as a hooker before moving to the back row and captained England at Under-19 level during 2001/02.
His last game for Tigers was in the Aviva Premiership victory over London Wasps at Welford Road in April.
Deacon has been advised to retire from the professional game after illness last season.
“I’ve had a very enjoyable career and it is disappointing when the decision to stop playing is taken out of your hands but I have to go with the medical advice,” said 31-year-old Deacon.
“Every young player growing up in the area wants to play for Leicester Tigers and I was fortunate enough to be able to do that, and to play for the club alongside my brother.
“I was a supporter on the terraces and ended up playing through the Academy and into the first-team which was all I ever wanted to do.”
Brett has been working with the Tigers coaching team season and also coached Cambridge University in their Varsity campaign.
Richard Cockerill, Tigers director of rugby, said: “Brett was a homegrown player who became an important part of the first-team squad here. He always gave everything for the team and is a Leicester Tiger to the core.
“It is important to have that ‘Leicester’ presence throughout the club and continuity. We wish him well in his new role working with the Academy.”
Deacon will work with Academy manager Neil McCarthy and assistant manager Tosh Askew in nurturing and developing talent at the club.
McCarthy said: “Brett has a lot of experience as a player at this club, from the junior teams right through to the first team, and we’re looking forward to seeing his work with our Academy players who want to follow his path into the senior team.”