Saleem Mairaj was born in Karachi, Pakistan. He began his career as a theatre actor and acted in various plays. He gained popularity through his debut television serial titled "Colony 52" which was aired on Pakistan Television Corporation (now PTV Home) in 1990s. He has since appeared in various television serials. His work in television includes Ishq Ki Inteha (2009), Kash Main Teri Beti Na Hoti (2011), Ullu Baraye Farokht Nahi (2013), Kise Apna Kahein (2014) and Kitni Girhain Baaki Hain (2014). Saleem made his Lollywood debut in 2007 horror film Zibahkhana. He has also starred in 2008 drama film Ramchand Pakistani and 2013 mystery thriller film Josh: Independence Through Unity. Saleem has made a cameo appearance in 2014 comedy film Na Maloom Afraad and in its sequel Na Maloom Afraad 2 (2017). He will appear in Upcoming Action-Comedy film Jhol, and in the horror flick Pari.