[2] The county is named for Henry Karnes, a soldier in the Texas Revolution.

[3] The former San Antonio and Aransas Pass Railway passed through Karnes County in its connection linking San Antonio with Corpus Christi.

[4] As of the 2020 United States census, there were 14,710 people, 4,552 households, and 3,156 families residing in the county.

24.40% of all households were made up of individuals, and 13.60% had someone living alone who was 65 years of age or older.

Around 2008 ConocoPhillips drilled a well in Karnes County and struck oil, causing an economic boom.