It also made an arrangement with National Educational Television to carry the first season of Sesame Street until WFYI (channel 20), the PBS member station in Indianapolis, signed on in 1970.

The other stations, all in Ohio, were the regional network's flagship WLWT in Cincinnati, WLWC (now WCMH-TV) in Columbus, and WLWD (now WDTN) in Dayton.

[10] On the same day as the switch, VideoIndiana, the Dispatch subsidiary that held WTHR's license, filed a $33 million antitrust lawsuit against ABC and WRTV's parent company McGraw-Hill, alleging that WRTV's switch was closely tied to an earlier ABC affiliation deal involving McGraw-Hill's San Diego station, KGTV.

[11][12] The switch to NBC eventually provided a major windfall for WTHR starting when the NFL's Indianapolis Colts moved from Baltimore in 1984; until NBC lost the rights to the NFL to CBS in 1998 (effectively moving the games to WISH-TV and later WTTV in 2015), WTHR aired the bulk of the team's regular season games under the AFC package.

[13] (The experiment, which lasted until the fall of 1992, was succeeded by similar efforts by KRON-TV and KPIX-TV in San Francisco, and KOVR in Sacramento later in the decade, though for WTHR, was also partly done to compensate for Indiana's long-term time zone adoption issues.)

Channel 13 first saw a significant ratings boost in the mid-1990s, buoyed by NBC's stronger programming as well as improvements in its news department.

[citation needed] On September 2, 2007, WTHR celebrated its 50th anniversary;[14] the station used the song "Carousels (Dreaming of Tomorrow)" by Columbus-based rock band Alamoth Lane in an image campaign to promote the event (the song was also used in a market campaign by Columbus sister station WBNS to promote its upgrade to high definition newscasts).

[20] Starting in August 2009, WTHR preempted regular programming on the subchannel for high school football and basketball games under the titles, Operation Football Live and Operation Basketball Live, with marketing support from VYPE High School Sports Magazine.

[26] Due to reception problems in parts of Central Indiana with its VHF digital signal (including in areas on the fringe of its Grade B coverage such as Bainbridge and Crawfordsville) that did not occur with stations broadcasting on the UHF band following the transition, WTHR filed a request with the FCC in June 2013 to increase its transmitter power to 77,000 watts, which would exceed the commission's maximum power limit in effect at the time.

[27] On June 11, 2019, Dispatch announced it would sell its broadcasting assets, including WTHR and WALV-CD, to Tegna Inc. for $535 million in cash.

The station also acquired the local rights to two Colts regular season games during the 2013 season between the San Diego Chargers (on October 14, which aired on ESPN's Monday Night Football—whose Colts broadcasts are normally carried over-the-air by WNDY-TV (channel 23)) and the Tennessee Titans (on November 14, which aired on NFL Network's Thursday Night Football).

WTHR occasionally runs special editions of its newscasts or its highlight program Sports Jam to cover Pacers or Fever games.

As WRTV did, NBC's prime time schedule and the race broadcast are transposed and air in reverse order, under a special dispensation from the network.

ET, IMS lifted the local blackout for the Indianapolis 500 for WTHR due to inclement weather causing a significant delay in the start of the race.

Combined with NBC's prime time lineup as a lead-in, WTHR's ratings saw a modest uptick in the 1980s and early 1990s, but not enough to get it out of third place.

In 1999, the station's Eyewitness News broadcasts surged past then-dominant WISH in several key timeslots, finishing in first place for the first time in its history.

The station's ratings lead—which WTHR emphasizes in the slogan it adopted upon taking first place full-time, "Indiana's News Leader"—began to narrow in 2010 as WISH-TV and Fox affiliate WXIN saw viewership gains that year as WTHR's ratings steadily decreased in certain timeslots, especially on weekday mornings.

Despite decreased ratings for NBC's prime time schedule since the 2004–05 season, WTHR remains in a close battle with WISH for the #1 slot in the 11 p.m.

The news share agreement with WNDY was terminated after that station was acquired by WISH-TV owner LIN TV Corporation in February 2005; on February 28 of that year, when WISH assumed production responsibilities for the WNDY newscast, WTHR began producing a 10 p.m. newscast for Pax TV owned-and-operated station WIPX-TV (channel 63, now an Ion Television O&O), which was cancelled five months later on June 30.

The station's news set at the time, which was built in 1997 with an eventual conversion to HD broadcasts in mind, underwent a refresh as part of the upgrade.

In June 2011, WTHR began offering newscast segments for free streaming on the Roku digital video player.

WTHR has received national honors for its news reporting over the years, including Peabody Awards for two 2006 reports, "Cause for Alarm" (an investigation into faulty tornado sirens in Indiana) and "Prescription Privacy" (an investigation of improper disposal of personal pharmacy records);[45] WTHR also earned a third Peabody for 2010's "Reality Check: Where Are the Jobs?

The station earned two national Edward R. Murrow Awards from the Radio-Television News Directors Association (RTNDA) in 2011, in the "Overall Excellence" and "Investigative Series" categories.