The team manager role will see Evans, aged 35, as the main day-to-day interface between players and coaches.
His coaching role will see him specialise in working with senior squad wings and full-backs as part of head coach Nigel Davies's team.
Evans played more than 340 games for Llanelli and the Scarlets in a career which lasted from 1993 to this year. His 125 tries put him on Llanelli rugby's top 10 try scorers list. Trimsaran raised, he won four Wales caps.
Nigel Davies said: "We want to build a coaching team with as many specialists as possible. Garan's talents as a wing and full-back are widely recognised and I look forward to him starting in his new role next week.
"He has been a Scarlet all his life and fully understands the region. As a player and a person he will have the respect of players and coaches - and I know he will instill in others all the values associated with Llanelli rugby."
Garan Evans said: "With a superb new stadium due to open shortly and a powerful new coaching staff assembled it's a particularly exciting time to be at the Scarlets.
"I'm honoured to have been given this opportunity to work as team manager and to develop as a specialist skills coach. I hope to play an important part in helping the region thrive in the evolving professional era."
Guinness PRO12
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