Formerly known as Ŭndŏk County (Korean: 은덕군; Hancha: 恩德郡), from 1977 to 2010.

The county borders the People's Republic of China to the northeast.

The level ground along the Tumen is developed, but approximately 80% of the county is forested.

Under Joseon period "Kyunghung", the ancient name of Undok, was one of the six post/garrisons (Korean: 육진; Hancha: 六鎭) established under the order of King Sejong the Great of Joseon in 1433, to safeguard his people from the hostile Chinese and Manchurian nomads living in Manchuria.

Kyŏnghŭng County is divided into 1 town ("Ŭp") 12 villages ("Ri") and 3 worker's districts ("Rodongjagu").