Matondkar while still studying at H.R. College. Shivdasani made his debut as an adult opposite Matondkar in Mast. The film became an instant flop although Shivdasani won the Zee Cine Award for Best Male Debut and the Star Screen Award for Most Promising Newcomer – Male for his performance in Mast. He earned critical acclaim for his performance. Mohammad Ali Ikram of Planet Bollywood praised his performance and wrote: "Newcomer Aftab Shivdasani comes across as a bit young and aimless when the movie opens, but as you watch the proceedings, you'll learn that this bit of casting makes perfect sense considering Kittu's immaturity and innocence." In 2001, Shivdasani made his comeback to acting with his second film, Vikram Bhatt’s Kasoor opposite the debutant Lisa Ray. Shivdasani played a negative role and shot to instant fame with his portrayal of Shekhar Saxena, a well-known journalist, who murders his wife. His performance in the film earned him a nomination for the Filmfare Best Villain Award and a Zee Cine Award for Best Actor in a Negative Role. Taran Adarsh of Bollywood Hungama noticed the improvement in his acting and praised his performance. "Aftab, as the suave publishing magnate, catches you unaware with a performance that is first-rate. His characterisation is dissimilar from the one he played in his debut-making venture Mast. His work should catapult him to the league of genteel artists." His next release of that year saw him paired with Ram Gopal Varma again after Mast in Love Ke Liye Kuch Bhi Karega, in which Shivdasani starred in a supporting role opposite Saif Ali Khan, Fardeen Khan, Twinkle Khanna and Sonali Bendre. Shivdasani's performance was applauded by Taran Adarsh and considered to be better than the other two heroes. Taran Adarsh wrote "Aftab plays to the gallery and gives a good account of himself. Aftab has an edge over the other two heroes because his character is mass appealing. His scenes with Johny Lever are simply superb." However, the film failed at the box office. His last release of the year was Rajiv Rai's Pyaar Ishq Aur Mohabbat, in which Shivdasani played Taj Bharadwaj, one of the three lead roles with the debutant Arjun Rampal and Suniel Shetty opposite Kirti Reddy. Shivdasani was praised by Taran Adarsh. "Aftab Shivdasani has an edge thanks to his lovable characterization. He is natural." Pankaj Shukla of SmasHits wrote "Aftab is impressive as usual