The district was established in 1898, but its name and the location of the district office has changed several times in its history. At first named Si Bua Thong, then Thung Yai, it was finally renamed Khao Saming when the district office was moved to Ban ThaKathon in Tambon Khao Saming. The present district office building was opened on 14 February 2000.
The district is divided into eight sub-districts, which are further subdivided into 66 villages. Two townships are in the district: Saen Tungcovers parts of the tambon Saen Tung, and Khao Saming covers parts of the tambon Khao Saming and Thung Nonsi. There are eight further tambon administrative organizations.