The station began as a radio classroom experiment in 1941 on the campus of what was then Humboldt State College, with broadcasts airing on KIEM for two months until the attack on Pearl Harbor. The radio program resumed in full in 1947, when KHSC-AM signed on as a 10-watt carrier current station. In January 1960, Humboldt State applied for the first non-commercial radio license on a California college or university campus. The new station signed on for the first time on October 17, operating at 10 watts on 90.5 FM. It became KHSU in 1972, shortly after Humboldt State was elevated to university status.
The station remained almost exclusively a student training ground until 1982, when it boosted its power to 100 watts and moved to 91.5 FM. At that point, the station began a gradual process of professionalization, picking up an NPR membership in 1984. It returned to 90.5 in October 1984, this time with a greatly increased signal of 9,000 watts. In 1988, facing the prospect of waiting five years to qualify for grants from the Corporation for Public Broadcasting, KHSU shuffled its budget in order to enable it to hire the five full-time employees it needed for CPB funding within only five months of applying.
KHSU-FM also has a long tradition of volunteer producers and show hosts programming music and public affairs shows. This tradition continues in 2010 with over 80 volunteers contributing to the stations' day-to-day programming. Over 68 hours of KHSU programming is locally produced every week. Volunteer music producers account for 63 hours of KHSU's programming. Former independent producers include Emmanuel Serriere and his weekly French radio program "Radio a la Carte".