The Korean War Service Medal is a decoration of South Korea which was first authorized in December 1950. Originally known as the Incident Participation Medal the medal was first authorized to South Korean troops who had participated in the initial counter-assaults against North Korean aggression in June of 1950.

In 1951, President Syngman Rhee ordered that the Incident Participation Medal be renamed as the War Service Medal and further authorized the decoration to any troops who were defending South Korea against invasion. In 1954, the South Korean government authorized the now called Korean War Service Medal to all United Nations troops who had fought in the Korean War between the dates of June 25, 1950 to July 27, 1953.

At the time of the Korean War Service Medal's presentation to U.N. troops, the United States of America declined to award the medal to U.S. soldiers based on uniform regulations of the time which curtailed the acceptance and wear of foreign decorations on U.S. military uniforms. The Korean War Service Medal faded into history and was not heard of again until 1999. At that time, the South Korean government proposed the decoration be reactivated and retroactively awarded to all Korean and U.N. veterans who had served in the Korean War. Planned presentations of the award were scheduled for June of 2000, on the 50th anniversary of the Korean War.

On August 20, 1999, the Korean War Service Medal was authorized for distribution and wear by service members of the United States military. The task of issuing the medal was assigned to Randolph Air Force Base while the National Personnel Records Center was responsible for providing documentation to verify eligibility and updating military records to show receipt of the award.

The Korean War Service Medal is a separate award from the similarly named Korean Service Medal and the Korea Defense Service Medal.