Thornfield is an unincorporated community in Ozark County, Missouri. It is 15 miles (24 km) northwest of Gainesville. It is located on Route 95 at the Little North Fork of the White River on the edge of the Mark Twain National Forest between Wasola to the northeast and Longrun to the southwest. Hammond, the site of the historic Hammond Mill, lies on the Little North Fork 2.5 miles (4.0 km) southeast of Thornfield. Although it is unincorporated, Thornfield has a post office with ZIP code 65762.
A post office called Thornfield has been in operation since 1878. The area has the name of the local Thornfield family.
Thornfield R-1 Elementary School lies about one mile east of the town on Route 95.