Kapoor started out in Parallel Cinema making his debut in the 1989 Kumar Shahani film Khayal Gatha. When he had trouble finding acting jobs in the 1990s, Kapoor began writing and directing shorts. He made his full-length directorial debut with Private Detective: Two Plus Two Plus One (1997), which had Irrfan Khan and Naseeruddin Shah in minor roles. In 2001, Kapoor got his big mainstream break-in Dil Chahta Hai, which starred Aamir Khan, as uncle of Preity Zinta’s character. He received international attention in Mira Nair’s Monsoon Wedding in which he played an abusive uncle. Since then, he has written, directed, and appeared in many critically acclaimed films including Corporate, Bheja Fry, and also as Muhammad Ali Jinnah in a UK television film The Last Days of the Raj in 2007. In 2003, he wrote and directed the independent film Raghu Romeo which he financed by sending e-mail requests for money to his friends. Although it was not a box office success, the film won the National Film Award for Best Feature Film in Hindi. Kapoor then directed and starred in Mixed Doubles, a film that deals with Swinging in contemporary Mumbai. In 2008 he directed a Sleeper hit called Mithya. Many international critics call it one of the greatest Black Comedy of all times, a rarely explored genre. He was also nominated for Best Performance by an Actor for Siddharth: The Prisoner at the 2008 Asia Pacific Screen Awards. In the year 2010, he has also starred in a Bengali movie Iti Mrinalini opposite Konkona Sen directed by acclaimed Bengali film writer Aparna Sen. Kapoor frequently collaborates with actors Vinay Pathak and Ranvir Shorey.