Kelso High School is a public high school in Kelso, Washington, United States.

The original Kelso High School was torn down in 1987.

In 2003, the building underwent extensive renovations and additions to accommodate the district wide change from junior high (7th-9th) to middle school (6th-8th) (Huntington and Coweeman).

[1] Kelso participates in the second-largest classification of high schools in the Washington Interscholastic Activities Association (WIAA) in the six-team Greater St. Helens 3A League.

KHS has a very long history and tradition with two local rivalries across the Cowlitz River in Longview; R.A. Long and Mark Morris high schools.