The 44-year-old director took to Twitter to congratulate Hrithik for his act as a blind man driven to avenge the murder of his wife in the Sanjay Gupta-directed movie.
He also wrote that as a helmer it was a treat for him to watch the actor put his best foot forward, only reflecting his growth with time.
Karan wrote, "As a filmmaker it's exhilarating to watch an actor deliver his best... .@iHrithik is a power house talent and is exemplary in #kaabil."
The "Ae Dil Hai Mushkil" director had worked with Hrithik in his 2001 film, "Kabhi Khushi Kabhie Gham".