Formed by the confluence of the South Yamhill River and the North Yamhill River about 3 miles (5 km) east of McMinnville, it drains part of the Northern Oregon Coast Range.

[4][6] It is likely that Yamhill was the 19th century white settlers' name for a tribe of Native Americans, a Kalapuya people who inhabited the region.

[2] The Yamhill people were among 27 bands and tribes moved to the Grand Ronde Indian Reservation, formally established in 1857.

Near Dayton, the river passes under Oregon Route 18 before skirting the city, which lies to its right at RM 5 (RK 8).

Below Dayton, the river enters the Willamette at its RM 55 (RK 89) south of Newberg.