The station was first on the air from 1946 to 1949 as WMMJ, playing big band music and sports, but it had financial difficulties and went off the air. WPEO signed on in August 1950, with its studios in the Jefferson Hotel downtown, and started its top 40 format in 1954, competing with 1290 WIRL. During this time, Harry Harrison was at WPEO as the "Morning Mayor of Peoria" and station manager. In 1959, he left for New York's WMCA, and WPEO switched to country music in 1960.
In 1970, WPEO was bought by the Pinebrook Foundation, Inc., a Pennsylvania-based non-profit corporation, and switched to a Christian radio format. As of 2009[update], its programming is based on paid time for various national Christian programming sources. It is still restricted to daylight hours to protect clear-channel stationKDKA in Pittsburgh.