The station first signed on the air on October 27, 1954, as WTVW (for its on-air slogan "Wisconsin's Television Window"). In early 1955, the station was purchased by the Hearst Corporation, publishers of The Milwaukee Sentinel and owners of WISN radio (1130 AM); the new owners changed channel 12's call letters to WISN-TV, after its radio sister (whose calls were derived from now-defunct newspaper The Wisconsin News, which merged with the Sentinel 15 years prior to its sign-on; the WTVW calls are now used by the CW-affiliated station in Evansville, Indiana). The station originally operated as a primary ABC affiliate with a secondary DuMont affiliation. WISN-TV lost the DuMont affiliation when that network ceased operations in 1956, leaving it exclusively with ABC.
Shortly after WISN introduced this logo, the 1961 affiliation swap was reversed on March 27, 1977, as channel 6's owner Storer Broadcasting had better relations with CBS than ABC after its San Diego station KCST (UHF channel 39, now an NBC-owned-and-operated station) disaffiliated with the network over a 4-year dispute stemming from its then-affiliation on Tijuana-licensed XETV, also on channel 6.