The station was launched in 1948 by the Johnston Broadcasting Corporation as a sister station to its Bessemer-based WJLD-AM. It originally mirrored the R&B, blues and gospel format of WJLD, led by deejay Roy Wood, Sr. In 1963 WJLN began a 24-hour broadcast, the first FM station to do so in Alabama. Lewis White's Jazz Workshop program, which had been simulcast on both stations, moved exclusively to WJLN-FM from 1965 to 1973.
By the end of the 1960s, WJLN was moving into more progressive rock in the evenings, led by deejay Jim "Father Tree" Young. Young conducted an on-air interview with poet Allen Ginsburg in 1972. The station's claim to fame came in 1973 when WJLN heavily promoted the debut album from California's otherwise little-known Buckingham Nicks. Those efforts translated into sell-out performances at Boutwell Auditorium and Fair Park that sustained the duo into their merger into Fleetwood Mac.
The station adopted a full-time album rock format that same year and changed its call letters to WZZK-FM. The format survived for a few years before WVOK-FM (K-99) arrived. WZZK-FM switched over to become Birmingham's first FM country station in 1978.