Mirza started his career in 1985 when he joined his brother Saeed Mirza and veteran director Kundan Shah to set a new production company called Iskra.
He made his directional debut with the 1989 television serial Circus starring Ashutosh Gowariker and Shahrukh Khan, who was a newcomer actor at the time. Since then, he has collaborated with Shahrukh Khan and Juhi Chawla in every other project in his career.
He made his first cinematic debut with Raju Ban Gaya Gentleman (1992) starring Khan and Chawla. The movie was inspired by Raj Kapoor's classic comedy Shree 420 (1955). The movie did pretty well at the box office. However, his next project, Yes Boss (1997) did fairly well at the box office and was well received overall.