KPSI-FM signed on the air on June 13, 1980; 44 years ago (June 13, 1980).[3] It was the FM counterpart to KPSI 1450 AM (now dark). They were owned by the KPSI Radio Corporation. KPSI-FM originally broadcast on 100.9 FM, powered only at 3,000 watts. At the time, the station aired a Top 40/Contemporary Hit Radio format branded as "KPSI-101" and later "Power 101."
In November 1991, the frequency was changed to 100.5, which also allowed KPSI-FM to boost its power to 25,000 watts. On March 19, 2002, KPSI-FM dropped the Top 40 sound, changing to its current Hot Adult Contemporary music format and "Mix 100.5" branding.