Trundle is taking up a role that includes work with the current squad on community and charity commitments, host matchday hospitality and become part of the Academy coaching set-up.
The 36-year-old, a cult figure among Swansea fans, returns to the club after three years away during which time he played for Neath, Preston North End, Chester and Marine, and he is excited by the prospect.
"Ever since I left the club for Bristol City way back in 2007 I always said that I wanted to come back at some stage in any capacity, so I am excited about the new role," Trundle said.
"There is an even bigger buzz at the club and throughout the city now with the club in the Barclays Premier League.
"Football is everything I know and love and to stay involved in the game is fantastic. To do that at Swansea is even better.
"I've always had an amazing relationship with the fans, on and off the field, better than anywhere else I've been.
"Nobody has touched my heart more than Swans fans and to work closely again with them in the community and on matchdays is going to be an amazing experience for me. It's going to be a pleasure."
Swans chairman, Huw Jenkins, added. "Lee was a great player and ambassador for this football club when he was here. I know what the club means to him and how much the fans adore him so we are all delighted to welcome him back in this new role.
"It's an interesting new role that will coincide with an exciting schools and community initiative we will be announcing soon."