[4] Her father, John Spratt, was born near Glasgow, Scotland, and became a merchant in New York and a speaker for the irregular assembly during the Leisler Rebellion in 1689.

After Spratt's death in 1697 she married again to one David Provoost (1670–1724), a merchant of Huguenot-Dutch ancestry who also served as the (24th) mayor of New York City.

After Mary's mother died in 1700, the Spratt children went to live with their maternal grandmother,[3] Cornelia DePeyster, a major merchant rated as one of the wealthiest people in New York in 1695.

[6] Mary's life was divided between caring for her growing family, continuing the Provoost mercantile enterprises, and supporting her husband's political career.

She traveled to Philadelphia and successfully convinced prominent lawyer Andrew Hamilton to represent Zenger in his New York libel case.

[2][9] She sold these goods in her own store and, during the French and Indian Wars, supplied William Shirley’s Fort Niagara expedition with food, tools, cannon, and boats.

[3] On October 15, 1711, seventeen year old Mary Spratt married Samuel Provoost (d. 1719), a younger brother of her mother's third husband.