Family sources said Gore, 84, a former MP, died at a hospital at Vasai in the neighbouring Thane district.
A pioneer and visionary, Gore was one of the last of the Socialist pillars in Mahrashtra.
Mrinaltai, as she is respectfully referred , Gore was elected to Parliament on a Janata Party ticket in 1977.
Gore belonged to that special set of women who took to politics in a period when it was virtually unthinkable for women to be involved in public work.
Influenced by Mahatma Gandhi's Quit India exhortation as a youngster, Mrinal chucked a promising career in medicine to devote herself to organizing the poor and the disenfranchised. For more than half a century, she has been involved with a series of organisations and leading protests both on the streets and in the corridors of power, focusing on women's rights, civil rights, communal harmony, and trade union activities.
Over a decade ago, in a protest against price rise, Gore led a rally of hundreds of women brandishing rolling pins from Churchgate to Azad Maidan in South Mumbai. The first time she held a similar protest on the issue was in 1972.
Gore and other colleagues of her husband Keshav set up the Keshav Gore Smarak Trust, which supports community-centered activities and social awareness campaigns and actions after he died in 1958.
In 1961, Gore contested the civic elections and won a seat in the Bombay Municipal Council. Fighting a hard battle, she eventually brought regular and adequate drinking water supply to the area. For this she earned the sobriquet 'Paniwali Bai'.
After she quit her course in medicine, Gore began a career in politics in 1947 when she joined the Rashtriya Seva Dal. She joined the Congress but left a year later and was part of the Socialist Party. She and her husband, Keshav Gore, also a socialist, worked on building better civic infrastructure for the masses.
The couple participated in the Goa liberation movement and the Samyukta Maharashtra movement and were jailed for leading protests and satyagrahas.
In 1972, Gore contested the Maharashtra Assembly elections on the Socialist Party ticket and won with the highest margin in the state. As an MLA, she took up issues such as atrocities on marginal farmers, Dalits, tribal people and women and was regarded as a real firebrand.
After the prices of essential commodities began skyrocketing, Gore was at the forefront in setting up in September 1972 the Anti-Price Rise Committee, which mobilised the largest-ever turnout of women since the Independence movement. She also led protests against the entry of United States giant Enron in the power sector and supported people displaced by the Narmada Dam.
After the Emergency, in 1977, Gore was elected to Parliament on Janata Party ticket. In 1985, she became an MLA again and took up the issue of banning sex determination tests.