South Carolina Highway 173 (SC 173) is a 1.570-mile (2.527 km) primary state highway in the U.S. state of South Carolina.

It serves to connect the town of Ridgeville with U.S. Route 78 (US 78).

SC 173 is a two-lane rural highway that connect the town of Ridgeville northeast to US 78.

The predominant features along the route are homes and forest.

In 1941 or 1942, it was extended east to SC 31 (current US 176), with an incomplete gap at the Dorchester-Berkeley county line.