She was 71 and breathed her last at a private hospital in Juhu where she was rushed last Sunday after severe breathing problems.
Since her condition was critical she had been put on a ventilator but failed to recover and expired around 1 p.m.
Currently, she was playing a prominent role in the television serial "Kulfi Kumar Bajewala" on a private channel.
In between, Sinha had been missing from the serial on account of her illness but bounced back a few weeks ago till her demise.
A major figure in Bollywood in the 1970s-1980s, comfortably straddling both the commercial and alternate cinema, Sinha was noted for her sad and somber roles as well as light and romantic films with many top actors of the era.
Among her other notable films were: "Hawas" (1974), "Chhoti Si Baat" (1975), "Mera Jeevana (1976), the crime-thriller "Inkaar", "Kitaab" (both 1977), "Pati, Patni aur Woh" and Basu Chatterjee's "Safed Jhooth" (both 1978), a horror flick "Saboot" (1980), "Love Story" and as a gangster in "Josh" (both 1981) and Salman Khan's mega-hit "Bodyguarda (2011).
Gracefully sailing into senior roles in films and television, she was seen in teleserials like "Kkavyanjali" (2005), "Haar Jeet" (2012), "Qubool Hai" (2012), "Isqh Ka Rang Safed" (2015), "Chandra Nandini" (2016) and lately in "Kulfi Kumar Bajewala" (2018 onwards), telecast on various entertainment channels.
Born in Mumbai on November 15, 1947, to film producer Rana Pratap Singh, she started her professional career as a model and even won the Miss Bombay contest, catching the eye of renowned filmmaker Basu Chatterjee, making her mark in the industry though she entered it post-marriage.
Though her first film was "Raja Kaka" (1974), it was Chatterjee's "Rajnigandhaa that year which catapulted her to fame, with the title song by Lata Mangeshkar still fresh in public memory.
"Inkaar" was another important crime thriller in which she was paired opposite the late actor Vinod Khanna and was a hit film.
In 1968, she was married to Venkateshwaran Iyer, and the couple has a daughter, Jhanvi.
After Iyer's death in 1996, she had quit acting for some time and entered into a wedlock with Netaji B. Salunkhe, a doctor, in a temple ceremony.
They lived in a flat in Andheri west, but soon afterwards the marriage soured with her husband allegedly torturing her and demanding money, resulting in a police case which she subsequently won.
( With inputs from IANS )