Owned by the Lake Huron Broadcasting Corporation and affiliated with CBS, the small local station did not provide primary service to the Flint area for its first two decades of operation.

[6] The station broadcast its first test pattern on April 5; though it had not announced it had started, phone calls reporting reception were fielded from various areas in Mid-Michigan.

[8] The station increased its effective radiated power to 207,000 watts in 1954, which came as part of an expansion of the television studios in Bridgeport Township.

In 1955, it filed with the FCC, charging that WJRT had chosen a transmitter site expressly to take away its CBS affiliation.

[18] The station changed channels to 25 on September 14, 1965; however, even after a power boost to 302,000 watts in 1969, Flint remained outside of its grade-A reception area.

[18][19] In 1969, WKNX-TV and WJIM-TV in Lansing filed a $7 million antitrust lawsuit against the American Research Bureau (ARB), a ratings service, and WNEM-TV and WJRT-TV.

They claimed that ARB had entered into an agreement with the two stations under which it would not publish separate ratings studies for the Flint and Saginaw–Bay City areas, only on a combined basis.

The new transmitter allowed the Flint–Tri-Cities market to be fully realized; it gave channel 25 primary coverage of Flint as well as Saginaw, Bay City and Midland.

[23] The upgrade made WEYI-TV among the most powerful UHF stations in the country, broadcasting from the tallest structure in Michigan.

Along with the technical facelift came a significant investment in channel 25's news infrastructure, which had been relatively modest under Lake Huron's stewardship.

Soon after taking over, Rust Craft sought to change this by hiring Dick Fabian, who had worked as a disc jockey at WKNX radio and a part-time reporter for channel 25, as the station's first full-time anchorman.

[29] In June 1977, the Ziff Corporation, parent of magazine publisher Ziff-Davis, made a bid for Rust Craft, primarily seeking its six television stations.

Ziff-Davis had previously hired I. Martin Pompadur, a former ABC executive, as part of the company's plan to acquire television stations.

[44] The 11 p.m. news was dropped in 1989 due to continued low ratings; while management at the time stated a desire to restore late news within six to eight months,[45] this never came to pass, and it was newsworthy when the station aired a late newscast for one week in August 1992 to cover the Buick Open and local elections.

The revamp was considerable for the station; Doug Pullen, the media columnist for The Flint Journal, noted that viewers "may be inclined to scoff" at the news and that several of his friends laughed when told of the changes.

[52][53] The NBC affiliation switch provided enough of a lift in ratings that it attracted a buyer: Smith Broadcasting Group, which purchased WEYI-TV and two other stations for $63.5 million in 1995.

For company president Bob Smith, a native of Bloomfield Hills, it was the first station he had owned in his home state.

[57] WEYI began broadcasting programming from The WB in overnight hours in 1999, after Superstation WGN ceased airing the network's shows nationally;[58] this ended in 2001.

[60] After constructing a 4,480-square-foot (416 m2) extension to its newsroom to provide adequate space for its increased staff,[61][62] the station expanded the newscast from 30 minutes to an hour in May 2001.

[72] Two years passed before channel 46 itself began broadcasting as WBSF in September 2006, in time for the merger of The WB and UPN into The CW.

[77] As part of the SAFER Act, WEYI-TV kept its analog signal on the air until June 26 to inform viewers of the digital television transition through a loop of public service announcements from the National Association of Broadcasters.

However, due to FCC duopoly regulations, since Sinclair already owns Fox affiliate WSMH, Sinclair transferred the license assets of WEYI to Howard Stirk Holdings (owned by founder and CEO of communications firm The Graham Williams Group, political commentator Armstrong Williams, whose Sunday morning talk show The Right Side is carried by WEYI) and of WBSF to Cunningham Broadcasting (WSMH took over the operations of both WEYI and WBSF through local marketing agreements when the deal was completed).

[82] Sinclair announced numerous layoffs at WEYI–WSMH in March 2023, which led to a major cut in news production from the stations.