[9] WLS participates as an Emergency Alert System primary entry point, serving northern Illinois and western Indiana.

Weekdays on WLS, two local talk show hosts are heard: Steve Cochran is in morning drive time.

The station's contemporary hit radio era from 1960 until 1989 saw WLS at a creative and ratings pinnacle headlined by personalities Dick Biondi, Larry Lujack, John Records Landecker and Bob Sirott.

[1] Just before the permanent station was ready, Sears began broadcasts on March 21, 1924, as WBBX with noon programs using the WMAQ studios.

[1] Sears broadcast test transmissions from its own studios on April 9, 10 and 11, 1924, using the call sign WES (for "World's Economy Store").

[1] On April 12, 1924, the station commenced officially, using the call letters WLS (for "World's Largest Store"), and broadcasting from its new studios in the Sherman House Hotel in downtown Chicago.

[15] For a few months after ABC's 1960 purchase of it and the format change, the "bright new sound" that began in May 1960 was broadcast from the Prairie Farmer Building.

[23] Starting in the 1930s, WLS was an affiliate of the Blue Network of the National Broadcasting Company (NBC),[24] and as such aired the popular Fibber McGee and Molly and Lum and Abner comedy programs (both produced at the studios of Chicago's NBC-owned stations, WENR and WMAQ) during their early years.

[4] Changes were made regarding AM frequencies in 1941 as a result of the North American Regional Broadcasting Agreement (NARBA); this moved WENR and WLS from 870 to 890 kHz.

[32][33] Mort Crowley was the first disc jockey under the new format, and the first song played was "Alley-Oop" by The Hollywood Argyles, four weeks before it debuted on the Hot 100.

[16][37][35][38] Star disc jockey Dick Biondi, a 1998 inductee into the National Radio Hall of Fame, was brought in from WEBR in Buffalo, New York.

[41] Other DJs who were brought in for the station's new format included Bob Hale from WIRL in Peoria, Illinois, Gene Taylor from WOKY in Milwaukee, Wisconsin, Mort Crowley from WADO in New York City, and Jim Dunbar from WDSU in New Orleans, Louisiana.

[46] In 1967, Larry Lujack joined WLS as a DJ, four months after he had started at the station's top competitor WCFL.

[48][47] In 1968, a mid-twenty-something Chuck Buell was recruited as the youngest on-air radio personality for a major market contemporary hit music station to date to host the early evening 6 p.m. to 10 p.m. show.

[56][57] Other DJs on WLS during its top 40 era included Joel Sebastian, Gary Gears, J. J. Jefferies, Jerry Kay, Yvonne Daniels,[58] Brant Miller, Tom Kent,[48] Steve King, Jeff Davis, and Fred Winston.

[16][45] Some of the production directors responsible for the sound of WLS were Ray Van Steen, Hal Widsten, Jim Hampton, Bill Price and Tommy Edwards.

John Rook was named "Program Director of the Year" in 1968 and 1969 as WLS was estimated attracting 4.2 million listeners weekly by Pulse research.

Other special editions of some Top 40 songs exclusively made for their broadcasting were done by the musicians themselves or sometimes by the WLS audio engineers.

[68] Another "WLS-only" version was a combination of Captain and Tennille's "Love Will Keep Us Together" and "Por Amor Viviremos", which featured alternating English and Spanish vocals.

[72][73] In 1984, Steve Dahl and Garry Meier's program was moved to WLS from WLS-FM, over the objections of the duo, who attempted to have their contract declared invalid.

[79] By 1987, WLS was airing adult contemporary music, liberally laced with oldies and standards, with talk programming at night.

[48][45][80] During the 1980s, Les Grobstein was hired as the first and only full-time Sports Director of WLS and broke the story of Cubs manager Lee Elia's famous tirade on April 29, 1983, after a loss to the Los Angeles Dodgers, which included 54 profanities.

The station served as the "flagship" broadcast outlet for the Sunday night, national political talk show, Beyond the Beltway with Bruce DuMont.

However, in what was described as an "eleventh hour decision", ABC canceled the planned format change due to convincing from local management.

[85] On Memorial Day, 2007, WLS took a cue from sister station WABC and ran a special day of musical programming, "The Big 89 Rewind", featuring live visits from Larry Lujack, Tommy Edwards,[86] Fred Winston, Chris Shebel, Jeff Davis, John Records Landecker, Tom Kent, and other DJs, sounders, and airchecks from the Musicradio era.

On January 2, 2017, the station added the on-air team of Bob Sirott and Marianne Murciano from WGN (AM); the former marking his return to WLS for the first time since 1980.

[97] On June 23, 2015, WLS announced that the station had picked up broadcasting rights for Chicago White Sox baseball starting with the 2016 season.

In addition, WLS had also picked up broadcasting rights for Chicago Bulls basketball, beginning with the 2016-17 NBA season.

The Bulls moved to WSCR, taking effect immediately at the start of February, while the White Sox shifted to WGN several weeks later.