Kabhi Khushi Kabhi Gham 

It's quite possible that no role of hers is as well remembered as that of 'Poo' in K3G. She played a glamorous diva who is Anali's (played by Kajol) younger sister. It was the beginning of a long and prosperous love affair with Karan Johar which continues until today.

The film was extraordinarily successful at the Box Office and won innumerable awards too. Kareena herself was nominated for a Best Supporting Actress Award for her role in the film and it grossed a total revenue of about 35 crores! Best of all, she didn't get even remotely lost in a cast filled with the likes of SRK, Hrithik Roshan, Amitabh and Jaya Bacchan and Kajol! Now that's no small feat.