The movie, being directed by Rahul Dholakia, will mark Mahira's Bollywood debut.
Shah Rukh's sweet message for the 30-year-old "Humsafar" actress came after Mahira shared her reaction to a recent Shah Rukh-Kajol still from their movie "Dilwale".
Mahira, who has been open about her admiration for Shah Rukh, had tweeted, "Uffff!You both, Uff!" to which the 49-year-old "Chennai Express" star replied, "@TheMahiraKhan just saw your tweet. 'Uff' we will look good in Raees too. Hope all is well with you and family."
"Raees", meanwhile, is set for a July 8 release.