She was born to a relatively wealthy family in the town of Nivelles, now in Belgium. According to her biographer, Jacques of Vitry, her parents disapproved of her strong interest in religion and her rejection of their luxuries. Her marriage at the age of fourteen, however, freed her of their influence and she quickly persuaded her husband that they should have a spiritual (i.e. celibate) marriage and seek the apostolic life. The couple gave up their possessions and moved to Willambroux to work at a leper hospital.**
It is at this point that her husband disappears from the story. Marie had begun to collect a community of women about herself, including a woman named Clementia, who seems to have acted as a companion and servant to her and who had followed her into the life of a beguine. Around the year 1207 Marie, followed by her companions, moved to Oignies to become a recluse attached to the community Augustinian canons there. It was here that she met Jacques of Vitry, who would become her spiritual advisor and who would later write her vita.
Marie lived an extremely ascetic life, eating and drinking little and physically injuring herself as an act of penance. In her final years she was frequently overcome with religious ecstasies. According to her biographer, she spent the last few days of her life singing a rather extraordinary song in which she not only glorified God, but gave explanations on several theological points. Her life and Jacques of Vitry’s account of said life would eventually help gain ecclesiastical approval for the beguines.
*Which is, in fact, the only major source on her life.
**It is entirely possible they may have founded said hospital.
Muessig, Carolyn. "Prophecy and Song: Teaching and Preaching by Medieval Women." In Women Preachers and Prophets through Two Millennia of Christianity, edited by Beverly Mayne Kienzle and Pamela J. Walker, 146-158. Berkeley: University of California Press, 1998.
Holböck, Ferdinand. Married Saints and Blesseds Through the Centuries. San Francisco: Ignatius Press, 2002.
Simons, Walter. Cities of Ladies: Beguine Communities in the Medieval Low Countries, 1200-1565. Philadelphia: University of Pennsylvania Press, 2003.
The Blessed Marie of Oignies - The Monstrous Regiment of Women
Marie of Oignies - Wikipedia