Gunpo City proceeded without any changes in its administrative districts or designation through the rule of Japanese Imperialism and even after the establishment of the nation since it became Nam-myeon, Siheung-gun on March 1, 1914 , but was promoted to Gunpo-eup, Siheung-gun on May 1, 1979 according to the Presidential Decree No. 9409 promulgated on April 7 of the same year.

Thereafter, the government separated Siheung-gun and promoted Gunpo-eup to Gunpo City on January 1, 1989 based on the Law No. 4050 (promulgated on December 31, 1988 ) for efficient regional management as the demand for administration increased day by day.