The woman, who took on the police as well as the West Bengal government in her fight for justice in the case known as the 'Park Street rape', died of multiple organ failure early on Friday at a state-run hospital in Kolkata.
A single mother of two daughters, the woman was admitted to Calcutta Medical College and was being treated at the hospital's critical care unit.
Hospital sources confirmed her death but they could not say whether she died due to encephalitis or meningitis. According to initial reports, she died of multiple organ failure.
The woman was gang-raped in a moving car in the city's Park Street area on February 6, 2012 by 5 young men who picked her up from outside a prominent night club. She lodged an FIR at the Park Street police station on February 9, 2012.
Kolkata Police in its chargesheet confirmed gang-rape and named 5 men. They were charged with gang-rape, voluntarily causing hurt and criminally intimidating the victim. The charges carry a maximum punishment of life imprisonment.
The case is being heard in-camera, which began in the first week of March 2013, at the city sessions court. In January, a Calcutta high court bench said the trial should be concluded "preferably by three months".
While 3 of the 5 accused - Nishad Khan, Sumit Bajaj and Nasir Khan - are behind bars, 2 others, including the prime accused, are still at large.
Ali and Nasir's brother Kader, one of the key accused, are yet to be arrested. Kader is believed to be in Bangladesh.
Chief minister Mamata Banerjee had courted controversy after she said that the hue and cry over the incident was an attempt to malign her government and the incident was fabricated. Trinamool MP Kakoli Ghosh Dastidar had suggested she was a sex worker and that the rape was the result of a "dispute between a client and the girl".
During the years following the incident, the woman frequently said that her life had become miserable. She claimed she lost her job after the incident and that avoiding curious glare and comments made her condition unbearable.
She wrote on her Facebook post last year that she was thrown out of a restaurant at Hazra in south Kolkata after she was identified.