Vonnoh was born in 1858 in Hartford, Connecticut and raised in Boston. He studied at the Massachusetts Normal Art School in 1875, and attended the Academie Julian in Paris in 1880. There he studied with Gustave Boulanger and Jules Joseph Lefebvre. In 1883, he returned to Boston where he taught at the Cowles School in 1884 and at the School of the Museum of Fine Arts in 1885. 

In 1886, he married, and he and his wife honeymooned briefly in Grez, France. The following year they returned to France, this time for a longer stay, and his work began to display a new direction. Vonnoh studied French Impressionism and was impressed by Claude Monet, whose influence can be seen in his works of colorful landscapes and bright flowers. His painting at this time also demonstrates the dichotomy of many American Impressionists. In 1891, he was back in Boston, converted to Impressionism, and later that year he held a one man show at the Williams and Everett Gallery which included many of the paintings he had done in France. 

Vonnoh returned to Pennsylvania in 1891 to teach at the Pennsylvania Academy of the Fine Arts, where he continued his enthusiasm for French impressionism. He maintained a commitment to academics, but also encouraged an Impressionistic aesthetic. At the Pennsylvania Academy he taught portraiture, where his instruction was very popular. Among his students there were Robert Henri, William Glackens, and Maxfield Parrish. He divided his time between teaching and painting, especially portraits, although he did landscapes as well. He married his second wife, the sculptor Bessie Potter, in 1899, and she is shown in a number of garden landscapes he painted. These paintings are rich in color, suggestive of his time spent in Grez, but his later works become more timid. Vonnoh died in Nice, France in 1933.