The station was originally launched in 1947 as CFRA-FM, simulcasting the programming of its AM sister station. In 1959, the station began airing some separate programming. Two years later, in 1961, the station's programming became fully independent of CFRA's, and the station adopted the callsign CFMO. CFRA and CFMO were subsequently acquired by CHUM Limited in 1968.
CHUM dropped the station's longtime easy listening format in 1992, adopting the current calls and the brand name Kool FM for its new hot adult contemporary/CHR format. The CFMO calls and format were picked up by CHEZ-FM Inc., and adopted on what is now CKBY.
In 2007, CTVglobemedia bought CKKL-FM along with the other CHUM Limited properties.