CBS Corporation is an American mass media corporation focused on commercial broadcasting, publishing, and television production, with most of its operations in the United States. The president, chief executive and executive chairman of the company is Leslie Moonves. Sumner Redstone, owner of National Amusements, controls CBS by way of his majority ownership of the company's Class A voting stock; he also serves as chairman emeritus. It is currently the world's fifth largest entertainment company in terms of revenue, after Comcast, The Walt Disney Company, Time Warner, and 21st Century Fox. The company began trading on the NYSE on January 3, 2006. Until then, the corporation was known as Viacom, and is the legal successor to said company. A new company, keeping the Viacom name, was spun off from CBS. CBS, not Viacom, retains control of over-the-air television (CBS, CW) and radio broadcasting, TV production and distribution, publishing, pay-cable, basic cable (Pop), and recording formerly owned by the larger company. CBS has its headquarters in the CBS Building (colloquially called "Black Rock"), Midtown, Manhattan, New York City, United States.

Viacom was created in 1971 as the television syndication division of CBS, and was spun off in 1971. However, in 1999, Viacom acquired its former parent, by this time also named CBS Corporation, formerly Westinghouse Electric. The prior CBS Corporation also owned CMT and The Nashville Network (now Spike), which remained Viacom properties after the 2005 split, but the prior CBS did not own UPN, Showtime, Paramount Television, Paramount Parks, or Simon and Schuster.

In March 2005, Viacom announced plans of looking into splitting the company into two publicly traded companies, amid issues of the stock price stagnating (although it was alleged that another main force behind the split was the Super Bowl XXXVIII halftime show controversy, which led to MTV not being allowed to produce any more halftime shows, they had also produced the show for Super Bowl XXXV, the first Super Bowl CBS aired since regaining NFL rights and becoming MTV's corporate sibling).

On June 14, 2005, the Viacom board of directors approved the split of the company into two firms. The CBS Corporation name would be revived for one of the companies, to be headed by longtime television executive (and Viacom co-President) Leslie Moonves, and would include CBS, UPN, Infinity Broadcasting, Viacom Outdoor, Showtime Networks, and Paramount's television studio.

The split was structured such that the "new" Viacom was spun off from the "old" Viacom, which was renamed CBS Corporation. In a sense, this was a repeat of the 1971 spinoff. However, in this case, CBS retained virtually all of the prior firm's broadcast TV assets, including its various syndication companies.

With the split, the two new companies began trading on the NYSE on January 3, 2006. Investors anticipated Viacom benefiting from the split, but instead, it dropped approximately 20 percent, while CBS rose 9 percent.

Announced in January 2006, CBS and DIC Entertainment signed a multi-year deal in which DIC bought the Saturday morning airtime as "CBS's Saturday Morning Secret Slumber Party". In June 2006, DiC added a production partner AOL's KOL. Thus block would be called "KOL's Saturday Morning Secret Slumber Party on CBS".

On January 24, 2006, CBS Corporation, and Warner Bros. announced that they were to create a new broadcast network, The CW Television Network. The network officially debuted on September 18, 2006. The network formally debuted on September 20 with the 2 hour premiere of America's Next Top Model. The network is the result of a merger of The WB (a Warner Brothers holding) and UPN (a CBS Corporation holding). CBS Corporation and Time Warner each own 50% of the network. Tribune Broadcasting (which previously owned a 25% stake on The WB) and CBS Corporation will contribute its stations as new network affiliates.

Three days after the announcement of The CW, on January 27, CBS announced that it was selling its Paramount Parks division. On May 23, 2006, CBS Corp. sold Paramount Parks to the Cedar Fair Entertainment Company. With this acquisition, Cedar Fair became the third-largest theme park operator. On June 30, 2006, Cedar Fair announced that it has completed its acquisition of Paramount Parks from CBS Corporation in a cash transaction valued at US$1.24 billion. The transaction included a 10-year license that allowed Cedar Fair to use the Paramount name in the parks through the 2017 season.

On February 7, 2007, CBS announced it was selling seven stations in Providence, Rhode Island, Austin, Texas, Salt Lake City and West Palm Beach, Florida to Cerberus Capital Management for US$185 million. It sold another station, WFRV-TV in Green Bay, Wisconsin, and its satellite station, WJMN-TV in Escanaba, Michigan, to Liberty Media on February 13, 2007. News reports estimate the deal at about US$234 million. CBS is swapping the stations and US$170 million in cash for 7.59 million shares of CBS common stock held by Liberty Media.

On September 29, 2016, National Amusements sent a letter to both the company and Viacom, encouraging the two companies to merge back into one company. On December 12, the deal was called off.

The board of directors of CBS Corp. include: