The back-to-back premiers announced Cronk has signed on to be a part-time specialist halves coach and will work with every playmaker coming through Roosters system next year.
Cronk, 35, retired following the NRL grand final after a third consecutive premiership with the Roosters and Storm.
The Tricolours have signed former Cronulla playmaker Kyle Flanagan as a replacement for the two-time Dally M medallist.
He's likely to partner premiership-winner Luke Keary in the halves with Lachlan Lam another option for Roosters coach Trent Robinson.