Longhorn Cavern State Park is a state park located in Burnet County, Texas, United States. The Texas Parks and Wildlife Department is administrator of the facility. The land for Longhorn Cavern State Park was acquired between 1932 and 1937 from private owners. It was dedicated as a state park in 1932 and in 1938 was opened to the public. In 1971, the park was dedicated as a National Natural Landmark.