Her father was a prominent attorney, and her mother was a descendant of Sir George Yeardly, who had been appointed governor of Virginia and was knighted by James VI and I in 1618. In 1872, Mary wed Robert Garrett, the oldest son of John W. Garrett, who was president of the Baltimore and Ohio Railroad and Robert Garrett & Sons Bank.
Throughout her childhood, she was educated by governesses and tutors and was not permitted to leave home without the accompaniment of a tutor or family member.
Though Mary divided her time among her homes in Mount Vernon, Baltimore, Uplands (her family’s estate), and Newport, Rhode Island in addition to maintaining a suite at the Plaza Hotel in New York City, she was an active participant in the civic life of Baltimore and contributed to various charitable pursuits. She established the Robert Garrett Hospital for Children at 27 North Carey Street as well as a training school for nurses attached to the hospital. While the hospital was turned over to the city in 1923, Jacobs continued to maintain the facility with her own funds and set up six free clinics under the direction of Doctor William South. Baer.
In 1928, she built and equipped the Hospital for Tuberculosis Children on the grounds of the Eudowood Sanitarium.
Jacobs supported the American District Telegraph Boys of Baltimore and served as the treasurer of the Aviator Club, which raised money for a sanitarium for tuberculosis in the Blue Ridge Mountains of Maryland. With her fortune, Mary Frick Garrett Jacobs amassed a collection of paintings, tapestries, miniatures, porcelain, and jades.
Her paintings included works by Rembrandt, Frans Hals, Charles Willson Peale, Pietro Perugino, Jacob Isaakszoon van Ruisdael, Jean-Baptiste Greuze, Bartolomé Esteban Murillo, Thomas Sully, and George Romney (painter). In 1934 Jacobs offered her art collection to the Baltimore Museum of Art under several conditions.
One of the conditions was that John Russell Pope would be the architect to design the wing in which her collection would be displayed, and the board acquiesced.
