State Route 81 is a state highway in the U.S. state of Utah. It is a short connector road, only 2.475 miles (3.983 km) long, that connects SR-30 with the town of Fielding in Box Elder County.

The route starts at its intersection with SR-30 south of Fielding in Box Elder County, Utah. It starts out travelling west, then meanders northwest for approximately 1 mile (1.6 km) before turning north as 4000 West and continuing until its terminus at Center Street in the center of Fielding.

The route was established in 1935 by the Utah state legislature.

The entire route is in Box Elder County.