Originally signed on the air on August 12, 1956, as a primary CBS affiliate, taking that affiliation away from WTVK (UHF channel 26, now WVLT-TV on VHF channel 8). It was originally owned by a consortium headed by J. Lindsay Nunn and his son, Gilmore Nunn, owners of WBIR radio (1240 AM, now WIFA; and FM 103.5, now WIMZ-FM). The station's call letters come from Jesse W. "Jay" Birdwell, who founded WBIR radio in 1941; Birdwell sold the station to the Nunns in 1944. The Nunns shared ownership with WBIR general manager John P. Hart; Knoxville residents Robert and Martha Ashe, and the Taft family of Cincinnati. In October 1959, the Tafts' broadcast subsidiary, Radio Cincinnati, Inc. (later known as Taft Broadcasting), purchased the remaining 70% of the WBIR stations outright from the other parties.
In January 1961, Radio Cincinnati, Inc. sold WBIR-AM-FM-TV to the News-Piedmont Company of Greenville, South Carolina, owner of WFBC-AM-FM-TV in its home city. In 1967, News-Piedmont merged with Southern Broadcasting to form the Southeastern Broadcasting Corporation. Soon afterward, Southeastern sold off most of its radio stations (including WBIR-AM-FM), purchased four more television stations and changed its name to Multimedia, Inc. WBIR-TV shared flagship status with WFBC-TV (now WYFF).
WBIR-TV added a heart located in the middle of its 1977 logo; the next logo has kept this same motif since. The station also received a new tagline called Straight from the Heart, which was also used by sister station WMAZ-TV (channel 13) in Macon, Georgia at that time. During this logo's run, channel 10 switched from CBS to NBC on September 10, 1988 due to WTVK (UHF channel 26, which moved to VHF channel 8 three months after the switch to become WKXT-TV; it is now WVLT-TV) having a weaker signal and ratings than WBIR-TV and NBC being the top-rated network at the time. The station also debuted a new tagline to promote the switch called NBC and Channel 10, A New Beat of the Heart. Multimedia merged with the Gannett Company in 1995. This logo was italicized for the station's newscasts.