On June 3, 1929, KOMO radio engineer Francis J. Brott televised images of a heart, a diamond, a question mark, letters, and numbers over electrical lines to small sets with one-inch screens—23 years before KOMO-TV's first regular broadcasts.

KOMO would likely have held the distinction of being the first television station in Seattle, and perhaps the nation, if it were not for the occurrences of the Great Depression and World War II.

KOMO was awarded the license in June 1953 after the KJR group dropped their bid,[5][6] and KOMO-TV first signed on the air only five months later.

[citation needed] In October 1958, however, NBC signed affiliation deals with King Broadcasting Company for their radio and television properties in Seattle and Portland, Oregon.

On the morning of May 18, he woke up at 3:00 a.m. in Seattle on a hunch that he would get some impressive video that day, and loaded up his news car and headed towards Mount St. Helens without anyone at KOMO knowing about it.

[12] His news video, which shows an advancing ash cloud and mud flows down the South Fork Toutle River, was made famous by its eleven-minute long "journey into the dark", six of those minutes of which were recorded in "total darkness" as Crockett narrated to what he thought would be his "last day on Earth."

The car he drove, with the remains of KOMO lettering still visible, is now a part of a Mount St. Helens Volcano Museum just outside Toutle.

[26] Prior to the sale, KOMO-TV had been the last television station in the Seattle market to be owned by local interests, having been built by Fisher from the ground up.

On March 18, 2014, KOMO-TV's news helicopter crashed at the Seattle Center, as it was taking off from Fisher Plaza around 7:40 a.m., falling onto at least one car.

[35] On May 8, 2017, Sinclair Broadcast Group entered into an agreement to acquire Tribune Media—owner of Fox affiliate KCPQ (channel 13) and MyNetworkTV affiliate KZJO (channel 22)—for $3.9 billion, plus the assumption of $2.7 billion in debt held by Tribune, pending regulatory approval by the FCC and the U.S. Department of Justice's Antitrust Division.

[44] On July 18, 2018, the FCC voted to have the Sinclair–Tribune acquisition reviewed by an administrative law judge amid "serious concerns" about Sinclair's forthrightness in its applications to sell certain conflict properties.

[45][46] Three weeks later on August 9, Tribune announced it would terminate the Sinclair deal, intending to seek other mergers and acquisitions opportunities.

In 1996, after years of fan protests, both KOMO-TV and KATU began clearing the entire Monday Night Football schedule live, regardless of the teams that were playing each week.

KOMO-TV's news division has consistently won awards for its reporting, and averages more wins per year than any Seattle television station.

The station's evening newscast has long been co-anchored by Lewis and Goertzen, and was praised by the Seattle Post-Intelligencer as being the "Best First-String anchor unit in town.

"[62] Following the presidential inauguration ceremony in 1993, Lewis became the first reporter to interview then-President Bill Clinton, which occurred at the White House.

The Open Mobile Video Coalition chose KOMO and independent station KONG (channel 16), and WPXA-TV and WATL in Atlanta to beta test the ATSC-M/H standard, which has since been officially adopted for free-to-air digital broadcast television with clear reception on mobile devices, which overcomes the defects of the original ATSC standard.

It is also seen out-of-market on Charter Spectrum in Ellensburg[74] (part of the Yakima DMA), with ABC programming and some syndicated shows blacked out due to the presence of local affiliate KAPP.