Having made his international debut for South Africa against Italy in 1999, Fleck moved to England in 2003.
The abrasive Bok played alongside 2009 Lion Lee Mears at Bath Rugby for two seasons before retiring from the game due to a persistent calf injury in August 2005.
Now 33, Fleck has been in direct opposition to a number of other members of Ian McGeechan's Lions squad, with the likes of Phil Vickery and Brian O'Driscoll having been adversaries at both domestic and international level.
After working as a columnist and within business and coaching at lower levels including the South African Student team since calling time on his playing career, Fleck will rejoin the side where he made his name as a player.
Fleck played in 56 matches for Western Province and 49 matches for the Stormers in the then Super 12. Current Western Province captain Jean de Villiers made his Currie Cup debut playing inside Fleck six years ago, while Fleck himself faced the Lions with WP back in 1997.
"I'm very excited to be back in the Western Province set up and working with the coaches and athletes again," said Fleck, who will join WP as senior backline coach.
"Province and the Blue and White Hoops have always been part of me and I am looking forward to making a contribution."