Hirani was born on 20 November 1962 in Nagpur to a Sindhi family. His ancestors originally belong to Mehrabpur, a city now in the Naushahro Firoz District, Sindh, of Pakistan. His father Suresh Hirani ran a typing institute in Nagpur. Rajkumar Hirani studied at St. Francis DeSales High School, Nagpur, Maharashtra. He did his graduation in commerce. His parents wanted him to be a chartered accountant, but he was keener on theatre and film.

In his college days he was involved with Hindi theatre. He had many friends in Nagpur's medical college and hence spent much time in theater at the college. Suresh had his son's photographs taken and sent him to an acting school in Mumbai. However, Hirani could not fit in and returned to Nagpur after three days. His father then asked him to apply to the Film and Television Institute of India in Pune, but the acting course had shut down and his chances of admission to the directorial course looked slim as there were far too many applicants. Hirani opted for the editing course and earned a scholarship.

Early work (1994—99, 2000)

Hirani tried his luck as a film editor for many years. Bad experiences forced him to shift to advertising, and he gradually established himself as a director and producer of advertising films. He was also seen in a Fevicol ad where some men and elephants were trying to pull and break a Fevicol plank, saying "Jor Laga Ke Haisha". He was also seen in the Kinetic Luna ad campaign created by Ogilvy & Mather.

He was doing fairly well in the advertisement industry, but he wanted to make movies, so he took a break from advertisement and started working with Vidhu Vinod Chopra. He worked on promos and trailers for 1942: A Love Story (1994). He edited promotions for Kareeb (1998). He got his first big opportunity as a film editor with Mission Kashmir (2000).