Sainte Genevieve County, often abbreviated Ste. Genevieve County, is a county located in the eastern portion of the U.S. state of Missouri. As of the 2020 census, the population was 18,479. The largest city and county seat is Ste. Genevieve. The county was officially organized on October 1, 1812, and is named after the Spanish district once located in the region, after Saint Genevieve, patroness of Paris, France.

Ste. Genevieve is a city in Ste. Genevieve Township and is the county seat of Ste. Genevieve County, Missouri, United States. The population was 4,999 at the 2020 census. Founded in 1735 by French Canadian colonists and settlers from east of the river, it was the first organized European settlement west of the Mississippi River in present-day Missouri. Today, it is home to Ste. Genevieve National Historical Park, the 422nd unit of the National Park Service.