Pennsylvania Route 117 (PA 117) is a 12-mile (19 km) long route starting at its southern terminus at US 322 and PA 72 in Cornwall. Its northern terminus is at US 422 in Palmyra.

The route is known as Iron Master Road, Main Street, Lancaster Road, and Forge Road and completely travels through Lebanon County. One section is concurrent with Pennsylvania Route 241 in Colebrook. PA 117 was signed in 1928.

PA 117 heads west from an interchange with US 322 and PA 72 into West Cornwall Township on Mount Gretna Road. It then angles to the southwest, passing through the borough of Mount Gretna, before entering South Londonderry Township. It heads west to the village of Colebrook, where it turns north onto Mount Wilson Road. It then forms a brief concurrency with Pennsylvania Route 241 before splitting from Mount Wilson Road, which carries PA 241 to the north, and heading to the northwest onto South Forge Road. It then heads to the north and crosses U.S. Route 322 in Campbelltown before heading north into North Londondery Township and into the borough of Palmyra, where it ends at U.S. Route 422.

The entire route is in Lebanon County.