[3] WPEN has local hosts days and evenings while carrying the nationally syndicated ESPN Radio network nights and some weekend hours.

[5] After the FCC created the current FM broadcast band on June 27, 1945,[6] the station was reassigned to 97.5 MHz on July 10, 1947.

[5] Nassau Broadcasting Company, owner of then-new AM outlet WHWH, purchased the station effective December 12, 1964.

In August 1975, Nassau Broadcasting owner Herb Hobler hired Phil Gieger as the General Manager.

Other WPST DJs over the years included John Mellon (aka Walt Ballard), Ed Johnson, Doug James, John Brown, Eddie Davis, Trish Merelo, Andy Gury, Brian Douglas, Mel "Toxic" Taylor, Jay Sorensen, Dave Hoeffel, Tom Cunningham, Michelle Stevens, Eric Johnson, Mark Sheppard, Andre Gardner, Phil Simon, Steve Trevelise, Joel Katz, Rich DeSisto, Lee Tobin, Steve Kamer, Lori Johnson, Mark DiDia, Bob Sorrentino, and Scott Lowe.

This made 97.5 a much more valuable property, one ripe for sale to a major-market broadcast company regardless of what format it might currently be running.

Nassau Broadcasting chose to leave the final necessary step, the actual relocation of the 97.5 transmitter, to the eventual buyer, which would turn out to be Greater Media.

Clear Channel's decision to drop smooth jazz from 106.1 left a format hole in the market, and Greater Media decided to fill it with a new version of WJJZ on 97.5.

At the station's start, it used Broadcast Architecture's syndicated "Smooth Jazz Network," with musician Dave Koz as the afternoon host, Program Director Michael Tozzi handling middays and Ramsey Lewis' morning show simulcast from WNUA in Chicago.

DJs from the old WJJZ were added over time, including Bill Simpson, Frank Childs, Teri Webb, Desirae McCrae, Al Winters and Lisa Fairfax.

On September 5, 2008, at 6:00 p.m., after playing Boyz II Men's "I'll Make Love to You", WJJZ began stunting with a loop of 15 songs, ranging from Blondie's "Heart of Glass" to Avril Lavigne's "Complicated".

On October 9, 2009, at 5 p.m., after playing Streetcorner Symphony by Rob Thomas, WNUW flipped to an FM simulcast of WPEN, with the new identity of "97.5 The Fanatic, Powered by ESPN".

Beginning with the 2012 NBA Playoffs, WPEN-FM became the flagship station for the Philadelphia 76ers, moving away from WIP-FM, where they were aired for years.

[10] In 2016, WPEN began airing Philadelphia Soul regular season games, in the Arena Football League.

[13] On February 21, 2023, the Philadelphia Union and the Beasley Media Group announced a partnership agreement to make WPEN the official radio broadcast partner of the team.

[15] The minimum distance between two Class B stations operating on first adjacent channels according to current FCC rules is 105 miles.

[16] WALK-FM and WPEN operate on the same channel and the distance between the stations' transmitters is 125 miles as determined by FCC rules.

WPEN's HD3 digital subchannel formerly broadcast a Spanish CHR format branded as "Supra Radio" (which was simulcast on translator W237EH 95.3 FM in Pennsauken, New Jersey).