Parrish was the son of painter and etcher Stephen Parrish. He began drawing for his own amusement as a child. His father was an engraver and landscape artist, and young Parrish's parents encouraged his talent. He entered into an artistic career that lasted for more than half a century, and which helped shape the Golden Age of illustration and the future of American visual arts.
. He spent most of his life at his New Hampshire home/studio at The Oaks He was by all accounts a charming and intelligent man whose writings add a great deal to the text in Ludwig's biography of him.
Launched by a commission to illustrate L. Frank Baum's Mother Goose in Prose in 1897, his repertoire included many prestigious projects including Eugene Field's Poems of Childhood (including 8 color plates) (1904) (see illustration) and such traditional works as Arabian Nights (including 12 color plates) (1909). Books illustrated by Parrish, in addition to those that include reproductions of Parrish's work—including A Wonder Book and Tanglewood Tales (including 10 color plates) (1910), The Golden Treasury of Songs and Lyrics (including 8 color plates) (1911) and The Knave of Hearts (including 23 color images) (1925) – are highly sought-after collectors items.
He had numerous commissions from popular magazines in the 1910s and 1920s including Hearst's, Colliers, and Life. He was also a favorite of advertisers, including Wanamaker's, Edison-Mazda Lamps, Fisk Tires, Colgate and Oneida Cutlery. In the 1920s, Parrish turned away from illustration and concentrated on painting for its own sake. Androgynous nudes in fantastical settings were a recurring theme. He continued in this vein for several years, living comfortably off the royalties brought in by the production of posters and calendars featuring his works. An early favorite model was Kitty Owen in the 1920s. Later another favorite, Susan Lewin, posed for many works, and was employed in the Parrish household for many years. Parrish himself posed for many images that featured male—and occasionally female—figures (see Potpourri, 1905).
In 1931, he declared to the Associated Press, "I'm done with girls on rocks", and opted instead to focus on landscapes. Though never as popular as his earlier works, he profited from them. He would often build models of the landscapes he wished to paint, using various lighting setups before deciding on a preferred view, which he would photograph as a basis for the painting (see for example, The Millpond). He lived in Plainfield, New Hampshire, near the Cornish Art Colony, and painted until he was 91 years old. He was also an avid machinist.