[2][3] Jacobi had a long career practicing medicine, teaching, writing, and advocating for women's rights, especially in medical education.

[7] At the time of Jacobi's birth, the family lived in London because her father George was establishing a branch office for his New York City publishing company, Wiley & Putnam.

As a teenager, Jacobi published short stories in The Atlantic Monthly from the age of fifteen, and later in the New York Evening Post.

For several months, she practiced clinical medicine with Marie Zakrewska and Lucy Sewall at the New England Hospital for Women and Children.

[4] In July 1871, Jacobi graduated with honors and was the second woman to receive a degree from École de Médecine of the University of Paris.

Jacobi also participated in research and became a professor in the new Women's Medical College of the New York Infirmary and Mount Sinai Hospital.

Jacobi received Harvard University's Boylston Prize in 1876 for an original essay, later published as a book, The Question of Rest for Women during Menstruation.

[12] Jacobi's essay was a response to Dr. Edward H. Clarke's earlier publication, Sex in Education; or, A Fair Chance for the Girls (1875), a book claiming that any physical or mental exertion during menstruation could lead to women becoming infertile.

[11] It expanded on an address she made in 1894 before a constitutional convention in Albany, and was reprinted in 1915 and contributed to the final successful push for women's suffrage.

Also in 1894, after the defeat of the women's suffrage amendment to the New York State Constitution, Jacobi was one of six prominent suffragists who founded the League for Political Education.

While Elizabeth Blackwell (1821–1910) viewed medicine as a means for social and moral reform, the younger Jacobi focused on curing disease.