Jaisohn returned to Korea once again after Japan's defeat in the World War II. The U.S. Military Government which was in control of the southern part of Korea invited him to serve as the chief advisor. As the date of the first presidential election was confirmed by the United Nations, Jaisohn was petitioned to run for presidency by 3,000 people including young Kim Dae Jung, but he refused in the end. Jaisohn felt that political unity was needed for a new nation despite his uneasy relationship with the president elect Syngman Rhee. He decided to return to the United States in 1948 and died in 1951 during the Korean War.