The station originally signed on in 1958 with a popular music format as KFMK, but later migrated to a classical music format. By 1967, KFMK moved to a Top 40 format, competing against KRBE and had a slight advantage over KRBE because it was in stereo, although the later had a stronger signal at the time.
By 1968, KFMK transitioned to become Houston's first progressive rock station, known as "Mother Radio" (a name later referenced by KLOL, which was known as "Mother's Family"). In early 1969, KFMK abruptly changed to a Christian format. The station reverted to Top 40 in the late 1970s. The format lasted until the station's abrupt 1991 flip.
In 1991, the station flipped to "The Box" with the new callsign KBXX and a rhythmic contemporary format (which was alternately referred to as "contemporary crossover"). It competed fiercely competed with longtime heritage urban station KMJQ until Clear Channel Communications bought KBXX in late 1994, then paired it with KMJQ the year after. Despite being rhythmic, KBXX's music selection moved more toward a mainstream urban direction, intense with hip hop and R&B music. Clear Channel spun off KBXX and KMJQ to Radio One in 2000.
KBXX was moved to R&R's Urban Contemporary Airplay panel in 2006, however it still remains on Mediabase's Rhythmic Airplay Panel. In spite of having an urban-driven playlist, the station retains its rhythmic format in order to target a multicultural audience in the Houston market.