The station began life in February 1976 as WEMO ("EMO" standing for East Moline) and playing adult contemporary music. In 1978, the station adopted a country format, with the call letters WZZC. A change in station ownership came in late 1982, and in January 1983, the station — while retaining the country music format — changed its call letters to WLLR.
During this time, WLLR began a slow climb toward becoming the Quad Cities market's top-rated radio station, a goal achieved in the late 1980s.
In March 1998, WLLR's country format swapped frequencies with 103.7 FM's oldies format. At the time of the switch, KUUL was formatting rock oldies from the 1950s through early 1970s, but the emphasis gradually shifted toward hits of the 1970s and at one time the 1980s, although the station always retained part of its 1960s library.
From 2001-2007, KUUL carried "The Bob & Tom Show" during its morning programming block after originally airing on the former WHTS-FM, but the show has since been switched to KCQQ. The move coincided with a new morning show teaming Steve Ketelaar and Mark Manuel. Following the 2002 holiday season, the station began adding 1980s hits to its library, dropping nearly all of its pre-1964 music, thereby tweaking the format to an oldies/classic hits hybrid similar to KQQL. That music mix remained in place through 2009, when – after a series of layoffs – the station began automating most of its programming through iHeartRadio's oldies stream; the playlist was shortened to only 1960s and 1970s hits, with approximately two dozen 1980s titles remaining. The only live on-air talent remaining were morning show hosts Mark Manuel and Steve Ketalaar.
During the holiday season (roughly, Thanksgiving to Christmas Day) from 2002–2007, KUUL switched to an all-holiday music format. The holiday format moved to KMXG since the 2008 holiday season.