Ernest Noel Posey was born in New Orleans on December 25, 1937. He earned his Bachelors in fine arts from Louisiana State University, followed by a degree in architecture from Tulane University. A move to New York for an advertising career inspired him to continue pursuing painting, and in 1966 he had his first solo exhibition at the Henri Gallery in Washington, D.C.

Two years later Posey relocated to San Francisco, where he began teaching at the California College of Art and the San Francisco Academy of Art University (as chairman of the Department of Fine Art). Over the next decade, he would work in filmmaking and public television directing, book illustration, and graphic design, in addition to painting. He also took up a position as business manager for the California Federation of Art Teachers, and was a mediator-arbitrator with California Lawyers for the Arts. He exhibited throughout the U.S., including at the Palace of the Legion of Honor, the National Collection of Fine Arts, the National Institute of Arts and Letters, the Santa Barbara Museum, and the San Jose Museum of Art, among others.

Posey divided his time between the San Francisco Bay Area and Mendocino County, where he built a cabin and a working studio. In the late 1970s he permanently relocated there, and focused his energies on painting, drawing, and assemblages for the next thirty years.

Ernest Noel Posey died in Willets, Mendocino County, California in 2007 on December 25, his 70th birthday.