The station signed on the air on October 9, 1968, as part of the Kentucky Educational Television network. The station became the twelfth educational television station in Kentucky, and the eleventh KET satellite to sign on. Two other satellite stations followed, WCVN-TVCovingtonin September 1969 and WKMJ-TVLouisville in September 1970. These satellite stations were strategically located to serve as much of the state as possible. WKMU was the default KET-aligned television station to serve the Paducah area and the Jackson Purchase region until 1978, when WDXR-TV was acquired and converted into an additional KET satellite station.
Digital television
The station's digital television companion signal, WKMU-DT, began broadcasting in May 2002, as with thirteen other KET stations – all except WKPC-TV and WKMJ-TV.
As part of KET's participation in the 2016–17 FCC Spectrum incentive auction, WKMU moved its digital signal onto UHF channel 17 on October 18, 2019.
Programming
Station IDs
Although Murray is the city of license for WKMU, its broadcast station ID identifies itself as "Channel 21, WKMU, Murray/Mayfield, Kentucky". Mayfield is included in the legal ID due to the transmitter site of WKMU being located in Graves County, with Mayfield being the closest city to the transmitter.
Availability
Over-the-air coverage
WKMU's transmitter is located along Merit Road just north of KY 80 near Farmington, in eastern Graves County. Although Murray is the city of license for WKMU, its legal station ID identifies itself as "Channel 21, WKMU, Murray/Mayfield, Kentucky". Mayfield is included in the legal ID as the closest city to WKMU's transmitter in Graves County. WKMU serves much of western Kentucky's Jackson Purchase region, which comprises the eight westernmost counties of the state. Additionally, the signal also covers western Trigg County, much of Lyon County, and central and southern portions of Livingston County. The signal also serves southern Massac County in southern Illinois, and Henry, Weakley, and parts of Obion counties in northwestern Tennessee, including Paris, Martin, and the Union City–South Fulton areas. The signal also serves parts of western Stewart County in Middle Tennessee. This benefits residents of Tennessee counties that could not receive Lexington-licensed WLJT-DT. WKMU's signal coverage overlaps with that of other KET stations: WKMA-TVMadisonville covers the eastern fringes of WKMU's signal coverage area, and WKPD Paducah largely overlaps WKMU's signal.
Cable carriage
KET is offered on all cable systems in the state of Kentucky. The statewide cable coverage includes Mediacom systems, Zito Media, and the WK&T Cable systems in the region, as well as Murray Electrical Systems. Mediacom lists WKMU as the KET station serving Cadiz, in Trigg County on its cable systems in that area even though that area is completely within range of WKMA instead. Only WKPD, along with Carbondale, Illinois-based WSIU-TV, are available on satellite television within the Paducah–Cape Girardeau market.