Robert Vonnoh's German immigrant parents brought him to Boston as a child. When he was five, his father was killed in the Civil War; his mother then took hom to Roxbury MA. In 1872 he began work at the Armstrong and Co. lithographic firm. During the evenings, he studied with Walter Smith and Charles C. Perkins at the Boston Free Evening Drawing School. Between 1875 and 1879 he followed the course of study at the Massachusetts Normal Art School. Upon graduating, he became a teacher at the Thayer Academy in South Braintree MA and in the Boston Free Evening Drawing Schools.
In 1881 Vonnoh decided to leave for study in Paris. For two years he attended the Acad‚mie Julian under Gustave Boulanger and Jules Lefebvre. He returned to teach in several Boston schools before being named to replace Frederic Crowninshield at the School of the Museum of Fine Arts in 1885. The following year he married Grace D. Farrell, and in 1887 the two left for France where they spent most of the next four years. Vonnoh settled in the Parisian suburb of Grez-sur-Loing, to which he repeatedly returned throughout his life. There he experimented with impressionist color and brushwork in landscapes which were considerably progressive in relation to his more conservative portrait work.
When Vonnoh returned to Boston in 1891 he assumed a teaching post at the Pennsylvania Academy of Fine Arts, moving to Philadelphia in 1892. That year he was also elected to the Society of American Artists. He left his position at the Pennsylvania Academy in 1896 and began to spend time at Rockland Lake NY, where he moved with his second wife, sculptor Bessie Potter Vonnoh, in 1899. Four years later, they took up a primary residence in New York City, spending the summers in Lyme CT. In 1907 Vonnoh returned to Grez for four years. He resumed painting portraits in New York in 1911 but continued to spend part of each year at Grez. World War I interrupted his French visits, and in 1918 he began two more years of teaching at the Pennsylvania Academy. By 1922, however, he was back at Grez, spending much of the rest of his life in France.