Maureen Paula O’Sullivan was the daughter of Mary (née Frazer) and Charles Joseph O’Sullivan, an officer in the Connaught Rangers who served in World War I. She attended a convent school in Dublin, then the Convent of the Sacred Heart at Roehampton (now Woldingham School), England. One of her classmates there was Vivian Mary Hartley, future Academy Award-winning actress Vivien Leigh. After attending finishing school in France, O’Sullivan returned to Dublin to work with the poor.
Maureen O’Sullivan was discovered by director Frank Borzage and her first screen success came in 1931 with Will Rogers in A Connecticut Yankee. Her most famous role was Jane in the Tarzan series, opposite Johhny Weissmuller. O’Sullivan had seven children (including Mia Farrow) with husband John Farrow.
Maureen O’Sullivan died in Scottsdale, Arizona, of complications from heart surgery on 23 June 1998. She was 87 years old. O’Sullivan is buried in the Most Holy Redeemer Cemetery in Niskayuna, New York, her widower’s hometown.