Sun Valley is a small city in Lamar County, Texas, United States.

U.S. Route 82 touches the southern part of the Sun Valley city limits.

According to the United States Census Bureau, the city has a total area of 0.2 square miles (0.4 km2), all land.

[1] The area drains south to Mulberry Creek, part of the Sulphur River watershed flowing east into Arkansas.

[7] The Texas Education Code specifies that all of Lamar County is in the service area of Paris Junior College.