Janko Komljenović studied medicine in Vienna. He worked as an assistant at the Surgery Department of Medical Faculty in Zagreb from 1926 to 1936. In 1936 he became the appointed chief of medicine of the surgery department in newly built regional hospital in Sušak.
He was recognized for his work on developing neurosurgery, thoracic surgery, urology and traumatology at the new hospital. Besides, he introduced endoscopic urology at the Sušak Hospital. He was an accomplished traumatology surgeon.
Komljenović joined the Partisan movement in 1943, and was found in charge of the Military Hospital for the Kordun region from 1944 until the end of the war.
After the war he was reappointed as the chief of medicine of the Surgery Department of Sušak Hospital in 1946, and in 1955, together with Dr. Ante Medanić, he became the first professor of surgery at the newly founded Faculty of Medicine in Rijeka. He retired in 1961.