Hartline was elected a Foreign Member of the Royal Society (ForMemRS) in 1966. He was awarded the Nobel Prize in Physiology or Medicine in 1967.
Hartline received his undergraduate education from Lafayette College in Easton, Pennsylvania, graduating in 1923. He began his study of retinal electrophysiology as a National Research Council Fellow at Johns Hopkins University, Baltimore, receiving his Doctor of Medicine (MD) degree in 1927.
After attending the universities of Leipzig and Munich as an Eldridge Johnson traveling research scholar from the University of Pennsylvania, he returned to the US to take a position in the Eldridge Reeves Johnson Foundation for Medical Physics at Penn, which was under the directorship of Detlev W. Bronk at that time. In 1940–1941, he was Associate Professor of Physiology at Cornell Medical College in New York City, but returned to Penn and stayed until 1949. Then he became professor of biophysics and chairman of the department at Johns Hopkins in 1949. One of Hartline's graduate students at Johns Hopkins, Paul Greengard, who also won the Nobel Prize. Hartline joined the staff of Rockefeller University, New York City, in 1953 as professor of neurophysiology.
Hartline was elected a Foreign Member of the Royal Society (ForMemRS) in 1966. He was awarded the Nobel Prize in Physiology or Medicine in 1967.
