By the 1990s, the WGN superstation feed began substituting some syndicated programs (and starting in 1996, selected sporting events) in accordance with syndication exclusivity rules implemented by the Federal Communications Commission (FCC) in January 1990 to reduce programming duplication between local and out-of-market television stations carried by local cable systems, and served as the national carrier of The WB (part-owned by WGN-TV founding owner Tribune Broadcasting, which would acquire the national feed from United Video in 2001) during the latter half of the decade.

The channel in its final form under the WGN branding ran a mixture of entertainment programs (consisting of comedy and drama series, and theatrical feature films) for most of the broadcast day and, beginning in March 2020, a straight-news format—via a daily national prime time newscast, NewsNation—during the evening and early overnight hours.

The station was also known locally for its lineup of children's programs including Bozo's Circus (which became the most well-known iteration of the Bozo franchise through its local and, later, national popularity, featuring a mix of comedy sketches, circus acts, cartoon shorts and in-studio audience participation games), Ray Rayner and His Friends (a variety show which featured animated shorts, arts and crafts segments, animal and science segments and a viewer mail segment) and Garfield Goose and Friends (a series hosted by Frazier Thomas as the "prime minister" to the titular clacking goose who designated himself as "King of the United States," which is considered to be the longest running puppet show on local television) as well as a robust lineup of feature films (showing as many as four movies – one in the morning, and two to three films per night – each weekday, and between three and six movies per day on weekends).

By the fall of 1978, WGN-TV was being distributed to 574 cable systems – covering Western, Central and Southern Illinois and large swaths of Indiana, Wisconsin, Michigan, Minnesota, Iowa and Missouri – reaching an estimated 8.6 million subscribers.

[43][44] On October 8, 1981, District Court Judge Susan Getzendanner denied injunctive relief to WGN Continental Broadcasting and dismissed the case against United Video, citing that it was not required to carry the station's teletext transmission.

The U.S. Court of Appeals for the Northern District of Illinois reversed Getzendanner's decision on August 12, 1982, ordering in a narrowly defined ruling that United Video must retransmit WGN-TV's VBI Teletext where the transmission was directly related to and part of the 9:00 p.m. news simulcast.

United Video also made contingency plans to put alternative programming on a second satellite to which it could switch to absolve any holes in the WGN-TV national feed's schedule by leasing part-time space for the affected time periods.

The WGN cable agreement resulted in The WB becoming the second American broadcast television network to use a cable-originated service to provide extended coverage in designated "white areas" without over-the-air affiliate clearances, and one of three network-to-cable undertakings stewarded by Jamie Kellner.

Conversely, in the Chicago market, WGN-TV chose only to air the network's prime time lineup, and exercised a right of first refusal to decline Kids' WB to offer a local morning newscast and an afternoon block of syndicated sitcoms aimed at a family audience on weekdays and a mix of locally produced news, public affairs and children's programs as well as paid programs on weekend mornings; this cleared the way for Weigel Broadcasting to cut a separate deal to air Kids' WB programs locally over group flagship WCIU-TV (channel 26, now a CW affiliate), an independent station that ran the block Monday through Saturdays from September 1995 until WGN-TV began clearing the block on its schedule in September 2004.

[69][70][71] As The WB's initial program offerings ran on Wednesdays for its first nine months of operation and its prime time schedule would not expand to six nights a week until September 1999, the superstation feed filled the 8:00 to 10:00 pm.

[72] By 1995, the WGN superstation feed was available to about 85% of all American cable systems, reaching approximately 35 million households; however, some distribution gaps remained well into the 2000s in parts of the Northeastern and Western United States (including in select major markets like Pittsburgh and the immediate New York City area).

The proposal would have also seen TCI provide additional programming (including library content from distributors through which parent company Liberty Media had held investments) and receive subscriber fees paid by participating cable systems.

The changes were made to increase its cable distribution outside the channel's traditional coverage area and position itself as a general entertainment network that programs to the entire nation, not just Chicago and the Midwest.

[90] With the Tribune Company undergoing ownership and management changes following its exit from protracted Chapter 11 bankruptcy reorganization proceedings on December 31, 2012, under the control of senior debt holders Oaktree Capital Management, JPMorgan Chase and Angelo, Gordon & Co. (a reorganization which also led to the eventual spin-off of the company's publishing division in August 2014 to focus on its broadcasting, digital media and real estate units),[91][92] Tribune announced plans to convert WGN America from a superstation into a conventional cable-originated entertainment channel, similar to TBS's transition to a traditional cable channel—albeit in a hybrid form as it continued to relay its programming over its Atlanta parent station for nine years afterward—in January 1998.

[93][41] Matt Cherniss was appointed as the first president and general manager of WGN America and Tribune Studios, a new production unit that was formed with the intent of producing some of the network's original content, on March 19, 2013.

Eastern Time, Dish Network removed Tribune Broadcasting's 43 television stations and WGN America from its lineup, after the two companies were unable to reconcile terms on renewing their existing carriage contract.

[116][117] The program draws partly from the broadcast and digital resources of Nexstar's television stations (including those acquired by Tribune Media, in addition to WGN America, several months prior).

[124] NewsNation continued to maintain a reduced schedule of entertainment programs acquired by the channel under the WGN America moniker in daytime and select overnight slots; beginning with the launch of the morning news program Morning in America in September 2021, additional news content has gradually been added to the lineup to replace the acquired entertainment shows as the channel's syndication contracts inherited by Nexstar through the Tribune purchase expire.

Nexstar exempted WGN-TV—along with KTLA and KRON-TV/San Francisco—from a 2023 corporate mandate requiring most of the group's stations to begin streaming all local programming on a two-hour delay from their initial live broadcast, in an attempt to maintain leverage with pay television providers in carriage negotiations.

WGN America then relegated its movie telecasts to Sunday afternoons and weekend late nights from September 18, 2010,[134] until prime time films returned on Tuesdays, Thursdays and Saturdays in May 2013.

Some of the programs shown as part of the block – which included series such as WKRP in Cincinnati, Newhart, ALF, Barney Miller and The Honeymooners – had previously aired on WGN prior to the re-implementation of Syndex, or even after the rules went into effect on the Chicago signal or/and the superstation feed.

[106][141] Ripley's statement immediately put into question the future of the slavery-era period drama Underground, which premiered on the network in March 2016 and ended its second season two days after the announcement of Tribune acquisition on May 10, 2017.

Reports stated that Underground's production company/distributor Sony Pictures Television would seek other network and streaming partners to continue the program; WGN announced its decision to cancel the series on May 30.

[189][190] Through WGN-TV's longtime partnership with the Muscular Dystrophy Association (MDA) as its Chicago Love Network station, WGN America had simulcast the charity's annual Labor Day weekend telethon each September from 1979 to 2012.

[191] Beginning at its inception via United Video's uplink of the WGN-TV signal for cable and satellite distribution, WGN America carried most sporting events produced and aired by its now-former Chicago broadcast parent.

[197][203][204][205] A judiciary panel with the Seventh Circuit Court of Appeals overturned the 1992 decision on September 10, 1996; as a consequence, WGN-TV chose to relegate the 35 Bulls games it was scheduled to air during the 1996–97 season exclusively to the Chicago area signal.

Even prior to the decision to remove sports from WGN America's schedule entirely, the channel had chosen not to air certain sports-related programming carried on the Chicago signal such as the Blackhawks' victory parade following its 2010 Stanley Cup championship win and a half-hour special paying tribute to the late Cubs player and broadcaster Ron Santo in 2011.

As part of the network's conversion from a superstation into a general entertainment cable channel, on May 30, 2014, Tribune announced that WGN America would phase out national carriage of WGN-TV-originated Chicago Cubs, Bulls and White Sox game telecasts by the end of that year.

[231] In April 1985, the Canadian Radio-television and Telecommunications Commission (CRTC) approved eligibility for the signals of WGN-TV and fellow American superstations WTBS, WOR-TV and WPIX to be retransmitted as foreign services by multichannel television providers within Canada.

While CRTC had approved the Chicago station's broadcast signal and its national cable feed for carriage on any domestic multichannel television provider, the conversion of WGN America from a superstation into an independent general-entertainment service and its resulting programming separation from WGN-TV led Tribune Broadcasting to announce on December 15, 2014, that it would terminate all Canadian distribution rights for WGN America, effective January 1, 2015,[235] a move likely done to comply with then-CRTC-enforced genre protection rules that prohibited domestic or foreign channels from maintaining a general entertainment programming format.