KPIX-TV (channel 5), branded CBS Bay Area, is a television station licensed to San Francisco, California, United States, serving the San Francisco Bay Area. It is owned and operated by the CBS television network through its CBS News and Stations division, and is sister to KPYX (channel 44), an independent station. The two outlets share studios at Broadway and Battery Street, in San Francisco's North Waterfront district; KPIX's transmitter is located atop Sutro Tower. In addition to KPYX, KPIX shares its building with formerly co-owned radio stations KCBS, KFRC-FM, KITS, KLLC, KRBQ and KZDG (all now owned by Audacy, Inc.), although they use a different address number for Battery Street (865 as opposed to 855).

KPIX signed on the air on December 22, 1948, the first television station in Northern California as well as the 49th in the United States. It was originally owned by Associated Broadcasters, owners of KSFO (560 AM). Initially, channel 5's signal was transmitted from the top of the Mark Hopkins Hotel on Nob Hill. It later moved to a transmitter tower shared with KGO-TV (channel 7) at the Sutro Mansion (which was located midway between Mount Sutro and Twin Peaks), and then to the Sutro Tower in 1973. KPIX's first master control room was in the attic of the Mark Hopkins Hotel (just above the "Top of the Mark" bar).

The station immediately joined CBS due to a deal KSFO's owners had worked out with the television network one year earlier. KSFO was CBS radio's Bay Area affiliate from 1937 to 1941, when Associated Broadcasters backed out of a deal for CBS to buy the station. When KSFO was still affiliated with CBS, it was originally slated to move to 740 AM, the frequency of San Jose's KQW. 740 AM was the last 50,000-watt frequency available in the Bay Area, and KSFO was to raise its power to 50,000 watts after moving to 740. However, after KSFO parted ways with CBS radio, the network moved its Bay Area affiliation to KQW and was not about to give up the advantage of owning the Bay Area's last available 50,000-watt station. After lengthy Federal Communications Commission (FCC) hearings, KSFO won the 740 frequency, but later decided to stay at 560 and concentrate its efforts on building a television station. It traded the 740 frequency to CBS in return for getting the CBS television network affiliation for the Bay Area. KQW remained at 740 and its call sign was changed to KCBS.

The station also carried programming from DuMont until that network folded in 1956. It even carried a few NBC programs until KRON-TV (channel 4) signed on on November 15, 1949, and programs from the short-lived Paramount Television Network, such as Frosty Frolics, Time For Beany, Cowboy G-Men and Bandstand Revue.

When KPIX's first competitor, KGO-TV, signed on on May 5, 1949, KPIX produced programs to welcome it into the Bay Area. KPIX cameras were used on the first episode of the CBS News program See It Now on November 18, 1951, which opened with the first live simultaneous coast-to-coast TV transmission from both the East Coast (the Brooklyn Bridge and New York Harbor) and the West Coast (KPIX-produced images of the Golden Gate Bridge and San Francisco–Oakland Bay Bridge), under the narration of Edward R. Murrow. Under its first general manager, Phil Lasky, KPIX gained an early reputation for news coverage, being noted for originating national CBS coverage of the Japanese Peace Conference of 1951 (the event which "officially" brought an end to World War II, similar to the function that the Treaty of Versailles served for World War I), held in San Francisco (for which Lasky was commended by then-CBS News president Sig Mickelson), as well as local news coverage of the 1953 crash of an Australian airliner while on approach to San Francisco International Airport, and a powder explosion a few weeks afterward at an explosives plant in suburban Hercules. In regards to sports programming, KPIX broadcast the first Bay Area sports telecast on December 22, 1948, with a Pacific Coast Hockey League game between the San Francisco Shamrocks and Oakland Oaks. KPIX originated the annual college football East-West Shrine Game for DuMont, and was the flagship station of the San Francisco Seals of the Pacific Coast League until 1954.

In 1952, KPIX and KSFO moved into a new building at 2655 Van Ness Avenue; KPIX moved out of the facility in 1979, when it relocated to a converted 1920s-era warehouse on the corner of Battery and Broadway streets (refurbished by the architecture firm Gensler), where KPIX remains to this day (KSFO moved to studios in the Fairmont Hotel, across the hall from the Tonga Room, in 1955). The studio on Van Ness Avenue (renamed to Bridge Studios after KPIX's departure) was the first building in San Francisco specifically built for television; the game show Starcade taped there after a pilot was taped at KRON-TV's studios (it was demolished in 2006 to make way for a condominium complex).

Westinghouse Electric Corporation bought KPIX in 1954 and ran it as part of the company's Group W broadcasting unit. During Westinghouse's ownership, KPIX was the company's only television station on the West Coast. Additionally, it was one of two VHF stations (along with Pittsburgh's KDKA-TV) that did not have a historic three-letter callsign, and along with WJZ-TV in Baltimore (until 2008) was the only one without a sister radio station with matching callsigns.

In 1994, Westinghouse was looking to make a group-wide affiliation deal for its stations as part of a larger plan to transform itself into a major media conglomerate after WJZ-TV lost its ABC affiliation to Scripps-owned WMAR-TV in an affiliation deal spurred by Fox's affiliation deal with New World Communications. Westinghouse negotiated with NBC and CBS for a deal. While NBC (the highest-rated network during much of the 1980s and 1990s) offered more money, CBS was interested in the programming opportunities Westinghouse offered, due to its own stagnation in programming at the time. CBS also offered a potential merger of their respective radio networks down the road (which ultimately happened), while NBC had abandoned radio in 1987. Ultimately, Westinghouse signed a long-term deal with CBS to convert the entire five-station Group W television unit to a group-wide CBS affiliation, making the San Francisco market one of the few major markets that were not affected by the affiliation switches.