Neetu Singh was born in Delhi in a Punjabi Sikh family. Her parents are Rajee Kaur and Darshan Singh. She lived in Shanti Building, Peddar Road, Bombay and attended the Hill Grange High School on Peddar Road.
Neetu Singh made her debut as a child actress with film Suraj in 1966, with Rajendra Kumar and Vyjanthimala as the lead pair. She was spotted by actress Vyjanthimala, in her dance school and she suggested T. Prakash Rao that Neetu be taken for the small uncredited role in the film Suraj. She starred as the child artiste in films like Dus Lakh, Waris,Pavitra Paapi and Ghar Ghar Ki Kahani. She reprised the role originally played by Kutty Padmini in Kuzhandaiyum Deivamum, in its Hindi remake Do Kaliyaan.
Two years after the success of the film Rickshawkaran, in 1973, R. M. Veerappan (Sathiya Movies) decided to remake his Tamil movie into Hindi as Rickshawala (1973). The original Tamil film was a major commercial success and won M. G. Ramachandran the National Film Award for Best Actor. The remake was directed by MGR's friend, K.Shankar with the actor Randhir Kapoor and the actress Neetu Singh. The director duo Krishnan-Panju, who had directed Do Kaliyaan, suggested K.Spaniards, that he can take Neetu Singh to rerpise the role played by Manjula Vijayakumar in the original. This paved the way for Neetu Singh's debut at the age of 15 as the lead heroine. However the remake was a flop. She took a small role as the dancer in Yaadon Ki Baarat (1973), which became a hit, and her dance number to the song Lekar Hum brought her so much attention that she was immediately offered lead roles again. In most films, Neetu was cast as the fun-loving daughter or the 'optimistic' or 'lively' girlfriend.
She acted with the top stars of her day.She was paired with her future brother-in-law Randhir Kapoor in Heeralal Pannalal (1978), Bhala Manus, Kasme Vaade, Dhongee and in the delayed Nikkamma. The film Nikkamma, begun in 1976, was finally released in 1983 as Jaan-e-Jaan and became a dud though the song composed by R.D.Burman - Tere Bina Mein Kuch Bhi Nahin Hoon was popular. She was also paired opposite actors like her future uncle-in-law Shashi Kapoor in hits like Deewaar (1975), Shankar Dada, Ek Aur Ek Gyarah and the dud Kala Pani(1980). She was paired opposite Rajesh Khanna in the action-comedy film Maha Chor, the suspense film Chakravyuha (1978 film) and in Punjabi film Sawa Lakh Se Ek Ladaun.
Neetu Singh formed a pair with her boyfriend and then husband Rishi Kapoor in 12 films of which Khel Khel Mein (1975), Rafoo Chakkar (1975), Kabhie Kabhie (1976), Amar Akbar Anthony (1977), Duniya Meri Jeb Mein (1979) and their guest appearance in Pati Patni Aur Woh (1978) were successful. The other films Zehreela Insaan (1974), Zinda Dil (1975), Doosara Aadmi (1977), Anjane Mein (1978), Jhoota Kahin Ka (1979) and Dhan Daulat (1980) were box office failures. She was paired with Jeetendra in Dharam Veer (1977), Priyatama, Chorni, Jaani Dushman (1979), The Burning Train and opposite Vinod Khanna in Sewak, Parvarish (1977), Maha Badmaash, Yuvraaj, Raj Mahal. She was paired with Shatrughan Sinha only in Kaala Patthar (1979) and Ab Kya Hoga (1977). Of the 55 films she did as the lead heroine from 1973 to 1983, 25 were box office hits. She regards her roles in films Chakravyuha, Chorni, Priyatma and Dhongee as her best.
Neetu was 21 when she married Kapoor in 1980. She was at the top of her career, having just been nominated for a Filmfare Award as Best Supporting Actress for Kaala Patthar (1979), but she retired. She dismissed allegations that she left the film industry, as part of the Kapoor tradition which forbids women from acting in films, claiming that it was her 'personal choice.'
She made a comeback to films after 26 years, appearing opposite her husband in Love Aaj Kal (2009), Do Dooni Chaar (2010), Jab Tak Hai Jaan (2012) and Besharam (2013). Singh and Kapoor were awarded Best Lifetime Jodi (couple) at the 2011 Zee Cine Awards ceremony.
On screen and off it, Neetu and Rishi Kapoor fell in love. They tied the knot on 22 January 1980 after a much publicized engagement that was the talk of Hindi film industry. The couple has two children: Riddhima Kapoor Sahni (born 15 September 1980) and Ranbir Kapoor (born 28 September 1982). Known as a fashion designer, Riddhima Kapoor married Delhi-based industrialist Bharat Sahni on 25 January 2006 and gave birth to a daughter named Samara on 23 March 2011. Ranbir Kapoor is an actor, who has established a career in Bollywood.
She was honoured by Walk of the Stars as her hand print was preserved for posterity at Bandra Bandstand in Mumbai.