South Carolina Highway 300 (SC 300) is an 11.460-mile-long (18.443 km) state highway in the U.S. state of South Carolina.

The highway connects Ulmer with the Barnwell area.

SC 300 begins at US 278 south of Barnwell and heads in a southeasterly direction, crossing over Hurricane Creek and Parker Branch.

It runs parallel with Caddins Branch through a small subdivision before it crosses over Wells Branch, leaving Barnwell County.

It becomes Wells Branch Road as it enters Allendale County before passing by Dry Branch Hunting Reserve before it enters the Ulmer city limits.