Footage taken on Nov. 10 shows the man crouching in bushes while holding toilet paper, and a woman beside him pulling down her white pants to relieve herself, The Korea Herald reported.
Local broadcaster JTBC reported that the incident took place at the stone walls of Gyeongbokgung, a popular tourist attraction in South Korea.
The person who filmed the scene told JTBC the pair appeared to be part of an overseas tour group that was nearby at the time.
"At the time, many Chinese group tours were visiting Gyeongbokgung," the informant said.
Police reportedly intervened to stop the act but did not detain or charge the individuals.
Under local law, defecating at a cultural heritage site can be a misdemeanor.
The incident has provoked online criticism, with netizens calling on tougher punishments against them.
Gyeongbokgung, also known as Gyeongbokgung Palace, was the main royal residence of the Joseon dynasty. Built in 1395, it is located in northern Seoul and served as both the home of the royal family and the seat of government. Today, it is a popular tourist destination.