Singh was born on 6 July 1985 into a Sindhi family. He has an elder sister named Ritika Bhavnani. Singh is the maternal cousin of actress Sonam Kapoor and producer Rhea Kapoor, daughters of actor Anil Kapoor and wife Sunita Kapoor (née Bhavnani). Singh explains that he dropped his surname Bhavnani, since he felt that the name would have been “too long, too many syllables”, thus downplaying his brand as a “saleable commodity”.
Singh always aspired to be an actor, participating in several school plays and debates. Once when he had gone for a birthday party, his grandmother asked him to dance and entertain her. Singh remembers that he suddenly jumped in the lawn and started dancing to the song “Chumma Chumma” from the 1991 Bollywoodaction film, Hum. He felt the thrill of performing and was interested in acting and dancing. However, after he joined H.R. College of Commerce and Economics in Mumbai, Singh realised that getting a break in the film industry was not at all easy, as it was mostly people with a film background who got these opportunities. Feeling that the idea of acting was “too far-fetched”, Singh focused on creative writing. He went to the United States where he received his Bachelor of Arts degree from Indiana University.
At university, he decided to take acting classes and took up theatre as his minor. After completing his studies and returning to Mumbai in 2007, Singh worked for a few years in advertising as a copywriter, with agencies like O&M and J. Walter Thompson. He then worked as an assistant director, but left it to pursue acting. He decided to send his portfolio to directors. He would go for all kinds of auditions, but did not get any good opportunities, while only getting calls for minor roles: “Everything was so bleak. It was very frustrating. There were times I would think whether I was doing the right thing or not.”
In January 2010, Singh was called for an audition by Shanoo Sharma, the head of the casting division for Yash Raj Films. They informed him that it was for a lead role in their film titled Band Baaja Baaraat, a romantic comedy set in the world of wedding planning.Aditya Chopra, the Vice President of YRF, later saw the audition tapes on video and was impressed by Singh’s acting, and decided that he fit the part of Bittoo Sharma, the hero of the film. However, the director Maneesh Sharma needed some more convincing and he was called for a few more auditions over the next two weeks until they were completely convinced of his caliber. After the two weeks of testing, Singh was confirmed for the role of Bittoo, with Anushka Sharma playing the female lead.
Singh described the role of Bittoo Sharma as a typical Delhi boy. To prepare for the role, he spent time with students at the Delhi University campus. Prior to the release of the film, trade analysts were skeptical of the film’s commercial potential, citing the middling response to Yash Raj Films‘ last few productions, the lack of a male star and the fact that the female lead, Anushka Sharma, was by then an “almost-forgotten” actress. However, Band Baaja Baaraat went on to become a sleeper hit. Singh’s portrayal of Bittoo was praised, with Anupama Chopra of NDTV writing that Singh was “pitch perfect in the role of the uncouth but good-hearted small town slacker who is a bit of a duffer when it comes to matters of the heart. The film earned approximately ₹214 million (US$3.2 million) at the domestic box office. At the 56th Filmfare Awards, Singh won the award for Best Male Debut.