May Gearhart was born to Stephen M. and Emma Gearhart in Sagetown, Illinois on 22 April 1872. Her family moved to Southern California before 1890. One of three artistic sisters, May had the most extensive art education. She attended the Los Angeles State Normal School (now the University of California, Los Angeles), the School of the Art Institute of Chicago, the California School of Fine Arts in San Francisco where she studied with Rudolph Schaeffer, and with Arthur Wesley Dow at Columbia University’s Teachers College. In 1930, May studied with Hans Hofmann at the University of California. Berkeley.

Gearhart began teaching art in Los Angeles schools in 1893. Between 1900 and 1903, she served as supervisor of art in the Berkeley, California school system. She then returned to southern California and worked as a supervisor and art teacher for the Los Angeles City School system until her retirement. May lived in Pasadena with her sister Frances and her neighbor, Benjamin Chambers Brown, taught her the techniques of etching. The Gearhart sisters and the Brown brothers, Benjamin and Howell, co-founded the Print Makers of Los Angeles. The earliest exhibitions of the Print Makers of Los Angeles took place in their studio but as the membership increased the annual exhibitions took place at the Los Angeles County Museum of Art.

May Gearhart was a member of and exhibited with the Chicago Society of Etchers, the Print Makers Society of California, the Pacific Art Association, the Prairie Print Makers, and the Society of American Etchers. Her work is represented in the collections of the Indianapolis Museum of Art, Indiana; and the National Museum of American History and the Smithsonian American Art Museum, Washington, D.C.

May Gearhart died in Altadena, California on 14 August 1951.