The station signed on the air in October 1969. Its original call sign was WGLB-FM. It aired a variety of programming over its first 34 years, including country music, Top 40 and Classic hits. Most of these formats were also simulcast on its former AM sister station, WGLB1560 AM.
For a time, WGLB-AM-FM carried various satellite-delivered syndicated formats, and in later years, they were mostly live and local. The classic hits-era slogan was "Retro Radio". WGLB-AM-FM briefly carried Don Imus's syndicated morning talk radio show from New York in the late 1990s. The stations languished at the bottom of the Milwaukee area ratings due to its location and limited signal, which did not penetrate the southern half of Milwaukee County.
Catholic programming
WGLB-FM was owned by Joel Kinlow until 2003. That's when he sold the station to Catholic broadcaster Starboard Radio, the forerunner to Relevant Radio. WGLB-FM signed off the air on May 21, 2003. Following a facilities upgrade, WPJP officially debuted on August 22, 2003. Kinlow continued to own 1560 AM, which retains the WGLB call sign and airs an urban gospel format.
WPJP's call letters changed to WSJP-FM on March 17, 2014, just over a month before Pope John Paul II, the station's namesake, was canonizedas a saint on April 27 of the same year.