The station has had the WJIM-FM calls continuously since it signed on in 1960. For over three decades, WJIM-FM broadcast an easy listening/beautiful music format, which evolved during the early 1990s into a soft adult contemporary sound. On Labor Day in 1995, WJIM-FM switched from AC to "Oldies 97.5." The change came days after WIBM dropped its longtime oldies format in favor of country to compete with WITL-FM. The station's "good times and great oldies" format was very popular in Lansing for over a decade, with the station consistently rated in the top ten (and frequently the top five) 12+ in the Arbitron ratings.
On September 13, 2005, crosstown competitor WHZZ 101.7 FM abruptly flipped from adult-leaning CHR as "Z101.7" to Variety Hits as "Mike FM." WJIM-FM stepped in to fill the Top 40 void in the market two days later, as "Oldies 97.5" signed off with Don McLean's "American Pie" at 10 a.m. on September 15 and "The New 97-5" (usually just called "97.5, Lansing's New Hit Music Station") debuted in its place. Longtime "Oldies 97.5" morning man Rich Michaels moved to sister station WMMQ. On September 7, 2007, the station repositioned from "The New 97-5" to "97-5 Now FM."
The WJIM call letters have a history in Lansing of being associated with Top 40 music, as WJIM-AM 1240 was a leading Top 40 station in Lansing during the 1960s as "Big Jim 1240."