Knox County is a county located in the U.S. state of Nebraska. As of the 2010 census, the population was 8,701. Its county seat is Center. In the Nebraska license plate system, Knox County is represented by the prefix 12.
The Lewis and Clark Expedition passed through the area on 4 September 1804.
The US Treaty with the Ponca tribe was signed at White Paint Creek on 9 June 1825.
Knox County was formed in 1854. It was named after Major General Henry Knox.