Mrinal Gore was elected Corporator to the Mumbai Municipal Corporation in 1961. She was popularly known as "Paniwali Bai" in Mumbai for her efforts to facilitate the supply of drinking water to thousands of people in her constituency of Goregaon during her tenure as corporator. Her political orientation started after coming in contact with Rashtrya Seva Dal which was the cultural wing of the Socialist Party. When the Praja Socialist Party (PSP) split in 1955, Mrinal joined Rammanohar Lohia and Madhu Limaye to form the Samyukta Socialist Party (SSP). She was active in the Samyukta Maharashtra Movement as well as the Goa Liberation movement.
She spearheaded the anti-price rise agitation along with Ahilya Rangnekar and others in the year 1972 using the rolling pin as a symbol of women power and protest, the same year she fought the state assembly elections and got elected as a MLA. She was the president of the Mahagai Pratikar Samyutka Samiti-The Anti-Price Rise Women's United Front that was formed on 13th September 1972 and spearheaded many of the anti-price rise campaigns in the city of Bombay. In the year 1972, the two Socialist factions the SSP and PSP had merged to form the Socialist Party.
During the emergency she was arrested in December 1975 and was detained under MISA and was released only after 15 months. In the elections held after the emergency was lifted, she got elected as a Member of Parliament with the slogan Paaniwali bai Dilli mein, Dilliwali bai paani mein.
In the year 1985, she was once again elected to the Maharashtra assembly and became leader of the opposition. During this stint she along with other socialist colleagues like Baburao Samant and Kamal Desai formed Nagari Nivara Parishad agitated and raised the demand of the implementation of the Urban Land Ceiling Act. After years of struggle the then chief minister Vasantdada Patil sanctioned a plot of land at Dindoshi for setting up of housing colony later named Sangharsh Nagar.