Singh made her Bollywood debut in 1983 with Betaab, an immensely successful film in which she was paired with Sunny Deol. This was quickly followed by a succession of hits, such as Sunny in 1984, Mard (which was the biggest hit of that year) and Saaheb in 1985, Chameli Ki Shaadi and Naam in 1986, Khudgarz in 1987, And Waaris 1988. and Singh made a successful pair in several films, not only with Sunny Deol, Sanjay Dutt, and Raj Babbar, but also with Anil Kapoor and Amitabh Bachchan, two leading actors of the 1980s. As well as playing leading roles, she also played supporting negative roles in films such as Raju Ban Gaya Gentleman (1992) and Aaina (1993). She also won the Filmfare Best Supporting Actress Award for the latter. Her comic timings are still remembered. She decided to retire into family life and quit acting after her appearance in the 1993 film Rang.

Singh married actor Saif Ali Khan in January 1991. Singh, who was raised as a Sikh, converted to Islam before marriage and the couple had an Islamic wedding. Twelve years younger than her, Khan is the son of former Indian test cricket captain Mansoor Ali Khan Pataudi, the ninth Nawab of Pataudi and actress Sharmila Tagore and is a member of the royal family of the erstwhile Bhopal State and Pataudi State . Despite controversies, they remained married. She gave up acting after her marriage to Khan. After thirteen years of marriage, the couple divorced in 2004.

Their only daughter Sara Ali Khan was born on 12 August 1995. and son Nawab Ibrahim Ali Khan on 5 March 2001. Sara graduated from Columbia University and their son Ibrahim Ali Khan is studying in England. Ibrahim was a child actor in the movie Tashan. Sara Ali Khan made her debut in the movie Kedarnath in 2018.

Singh returned to acting in 2002 with the film 23rd March 1931: Shaheed, in which she played the mother of Bhagat Singh (played by Bobby Deol). She joined the television industry with Ekta Kapoor’s family drama Kavyanjali, aired on Star Plus in 2005. Singh was seen in a negative role in the show, that soon gained immense popularity. Later that year, she won acclaim for her performance in yet another negative role for the film Kalyug. In 2007, Singh played the role of gangster Maya Dolas’ mother, Ratnaprabha Dolas, in the Sanjay Gupta film Shootout at Lokhandwala, directed by Apoorva Lakhia. Vivek Oberoi played the role of Maya Dolas. Later on she appeared in the anthology film Dus Kahaniyaan, where she appeared in the short story Poornmasi.

Continuing her acting journey, Singh played in the film Kajraare in 2010, and also appeared in Aurangzeb under the Yash Raj Films banner, where she was paired with Jackie Shroff after almost two decades. In 2014, she was seen in the film 2 States, produced by Dharma Productions, portraying the role of co-actor Arjun Kapoor’s mother. The film released on 18 April 2014. In 2016, she appeared in Flying Jat playing Tiger Shroff’s mother and recently in 2017 she appeared in the acclaimed drama Hindi Medium. She played the Principal’s role for a glance. She was recently seen in Sujoy Ghosh’s Badla, released on 8 March 2019. She played the role of Rani Kaur.