Nicholas Dunphy was born in Seward, Nebraska on July 4, 1896, the son of a U.S. senator. Dunphy moved to Campbell, California in 1906 with his family. After graduating from high school, he enrolled at Stanford University where he studied art under Henry Varnum Poor and Robert Harshe. He had further training at the California School of Fine Arts in San Francisco where he later became the secretary-treasurer for over 25 years.

Most of his life was spent as a resident of San Carlos while maintaining a commercial art studio in San Francisco.  Primarily an etcher, he also painted portraits and landscapes of the San Francisco Bay area. Dunphy was a member of the California Society of Etchers; Palo Alto Art Club; California Printmakers Society; Southern PrintMakers Society; San Francisco Art Association; and the Society of American Etchers.

Nicholas Dunphy died in San Carlos, California on Jan. 24, 1955.