After home-tutoring she was married off in 1735 as the third wife of the much older Grand Marshal of Lithuania, Duke Paweł Karol Sanguszko (1682–1750).

That same year she procured the services of a French tutor, C. F. Pyrrhys de Varille, who remained on the estate in Lubartów, virtually continuously until her death.

Following the premature death of her daughter, Krystyna, she took charge of her granddaughter, Tekla Teresa, whom she educated in the French manner.

Every two years in the summer months she organised an élite Enlightenment salon in Poddębice attended by distinguished guests.

Together with Bona Granowska and her sister, Maria Lanckorońska, she formed 'the trinity of devout ladies' famed for their piety and philanthropy.

Barbara Sanguszko translated into Polish two religious tracts by Louise de La Vallière, former French royal mistress turned Carmelite nun, published in Lublin in 1743.