Jansen is an unincorporated community and a census-designated place (CDP) located in and governed by Las Animas County, Colorado, United States.

The population of the Jansen CDP was 101 at the United States Census 2020.

[3] The Trinidad post office (Zip Code 81082) serves the Jansen postal addresses.

[4] Jansen is located in western Las Animas County in the valley of the Purgatoire River.

Colorado State Highway 12 passes through the community, leading northeast 2 miles (3 km) to Trinidad, the county seat, and west 5 miles (8 km) to Cokedale.