Her work also touched on broader issues of human rights and democracy in the Arab and Muslim worlds.
Her best known work, Beyond the Veil, examines Islam from a feminist perspective and critiques traditional, male-dominated interpretations.
The writer, 75, reportedly died in a clinic in the capital Rabat.
Fellow Moroccan sociologist Sumaya Naaman Guesus told the Efe news agency that Mernissi was "the first woman to have the great courage to take up various themes considered taboo around the interpretation of the Koran and the texts of the Islamic tradition".
Moroccan-American author Laila Lalami was among many others who paid tribute to Mernissi, writing that "in addition to being a wonderful scholar, Fatema Mernissi was a kind and generous human being. A rare combination."
Mernissi's work drew attention to the active political role played by women in the early history of Islam, for example in her book The Forgotten Queens of Islam.
She contrasted this with claims of some conservative Islamists that the idea of a female political leader was un-Islamic after Pakistan elected its first female Prime Minister, Benazir Bhutto, in 1988.
The Moroccan writer and sociologist Fatima Mernissi, known for her pioneering work in the field of Islamic feminism, has died.