Evelyn Small Henson of Lancaster, South Carolina, was born on 16 February 1922 to a barber and a homemaker. After graduating from Lancaster High School, she attended Mercy Hospital Nursing School in Charlotte, North Carolina, for three years. After graduating in 1943, Henson immediately joined in the Army Nurse Corps.
Henson was commissioned a second lieutenant and went directly to the hospital at Camp Gordon, Georgia. Henson remained at Camp Gordon as a general duty nurse until August 1945, when she was transferred to Fort Bragg, North Carolina, for a few months until she resigned her commission in early 1946.
Hensen attended the Peabody School in Nashville, Tennessee, for one year before transferring to the University of North Carolina at Chapel Hill, where she received a bachelor of science in public health nursing in 1950. She worked as a public health nurse in Hillsborough and Greensboro, North Carolina, for several years before raising a family.