Yornup's name is of Noongar Aboriginal origin. It was primarily a milling settlement, and Greenacres Mill continues to this day. A timber company, Lewis and Reid, built a mill in town that was sold in 1923 to Bunning Brothers who upgraded the mill in 1935 and continued to operate until 1951 when the Donnelly River mill commenced operations.
A railway line between the Donnelly Mill and Yornup was built in 1948 and remained in use until the last steam train was retired in 1970.
At one point, Yornup had a school, post office, hall and stores - only the hall remains today, used for community dances. The school was relocated to the rear of 144 Hampton Street, Bridgetown, in March 1996 in anticipation of the construction of a heritage precinct which never eventuated. A large Western Power substation is located in the town and an industrial estate is proposed for the area.