Willamina Creek is a tributary, about 20 miles (32 km) long, of the South Yamhill River in the U.S. state of Oregon.

Veering south again, it flows through segments of Tillamook State Forest before re-entering Yamhill County about 13 miles (21 km) from the mouth.

Turning east at Willamina, it enters the South Yamhill River about 43 miles (69 km) from the larger stream's mouth.

[6] It estimates the average discharge at this point at 150 cubic feet per second (4.2 m3/s) with the highest flows in winter and spring.

[8] The creek offers catch-and-release fishing for wild cutthroat up to 11 inches (28 cm) long.