Christy, born in 1873, grew up on his family farm in Duncan Falls, Ohio. At sixteen, he went to New York City to study at the Art Student's League, and after less than four years he entered the National Academy of Design where he won two prizes in draughtmanship.
Christy worked for Scribner's Magazine, a current events magazine, as an illustrator for a number of years beginning in 1898. In addition to illustrating articles and stories, Christy also traveled to Cuba and Puerto Rico and sent back illustrations of Spanish-American War activity. It was through this work as a commercial artist that he became a nationally known illustrator.
After his return to the United States, he taught for a brief time in New York, however, he soon returned to his hometown of Duncan Falls. There he built a studio and summer home and divided his time between painting and entertaining visiting authors and publishers.
While living in Ohio during this time, he became famous for his stylized depictions of women, popularly known as "Christy Girls." These illustrations appeared in many publications and print art, and were eventually used on recruitment posters for Word War I.
By 1915, he had returned once again to New York City and soon took up portrait painting. His portrait subjects included President Coolidge, Eddie Rickenbacker, Douglas MacArthur, Amelia Earhart, Herbert Hoover, and Benito Mussolini. Later in life Christy began painting large historical works. He was commissioned in 1945 by the state of Ohio to paint "The Signing of the Treaty of Greene Ville," which today hangs in the Ohio Statehouse in Columbus. His most famous of these large compositions, "The Signing of the Constitution of the United States" is located above the grand staircase in The Capitol in Washington DC.
Christy died in 1952 at his apartment in New York.