By 1926 the market for commercial radio had expanded, and RCA purchased the WEAF and WCAP radio stations and networks from AT&T, merged them with its WJZ (the predecessor of WABC) New York to WRC (presently WTEM) Washington chain, and formed the National Broadcasting Company (NBC).

In 1929, RCA purchased the Victor Talking Machine Company, then the world's largest manufacturer of phonographs (including the famous "Victrola") and phonograph records. This included a majority ownership of the Victor Company of Japan (JVC). The new subsidiary then became RCA Victor. RCA Victor produced many radio-phonographs and also created RCA Photophone, a sound-on-film system for sound films that competed with William Fox's sound-on-film Movietone and Warner Bros.' sound-on-disc Vitaphone. RCA began selling the first electronic turntable in 1930. In 1931, RCA Victor began selling 33⅓ rpm records. The system was withdrawn from the market after about a year.

In 1930, the U.S. Department of Justice brought antitrust charges against RCA, General Electric and Westinghouse. As a result, General Electric and Westinghouse gave up their ownership interests in RCA. RCA was allowed to keep its radio factories, and General Electric and Westinghouse were allowed to compete in that business after 30 months.

RCA demonstrated an all-electronic television system at the 1939 New York World's Fair, and developed the USA's first television test pattern. With the introduction of the NTSC standard, the Federal Communications Commission authorised the start of commercial television transmission on July 1, 1941. World War II slowed the deployment of television in the United States, but RCA again began selling television receivers almost immediately after the war ceased.

RCA was a major producer of vacuum tubes (branded Radiotron) in the United States, creating a series of innovative products ranging from octal base metal tubes co-developed with General Electric before World War II to the transistor-sized Nuvistor used in the tuners of the New Vista series of TV sets.

In 1941, before the attack on Pearl Harbor, the cornerstone was laid for a research and development facility, RCA Laboratories in Princeton, New Jersey, led for many years by Elmer Engstrom. This lab developed many innovations, such as colour television, the electron microscope, CMOS-based technology, heterojunction physics, optoelectronic emitting devices, liquid crystal displays (LCDs), videocassette recorders, direct broadcast television, direct broadcast satellite systems and high-definition television. From 1988 to January 2011, the Lab was called Sarnoff Corporation, a subsidiary of SRI International, after which it was fully integrated into SRI.

In 1949, RCA Victor released the first 45 rpm record to the public, to compete with CBS/Columbia's 33⅓ rpm "LP" format. The RCA 33⅓ rpm "LP" records themselves became a reality in 1950, and in 1951, so did the CBS/Columbia 45 rpm record.

In 1953, RCA's all-electronic color TV technology was adopted as the standard for American color TV. It is now known as NTSC (after the "National Television Systems Committee" that approved it). RCA cameras and studio gear, particularly of the TK-40/41 series, became standard equipment at many American television network affiliates, as RCA CT-100[23] ("RCA Merrill" to dealers) television sets introduced color television to the public.

RCA was one of several major computer companies, and marketed the Spectra 70 Series and the RCA Series (RCA 2, 3, 6, 7) competing against the IBM System/370. These systems all ran RCA’s real-memory operating systems, DOS and TDOS. RCA’s virtual memory systems, the Spectra 70/46 and 70/61 and the RCA 3 and 7, could also run their Virtual Memory Operating System, VMOS. RCA abandoned computers in 1971. Sperry Rand officially took over the RCA base in January 1972.

RCA Graphic Systems Division (GSD) was an early supplier of electronics designed for the printing and publishing industries. It contracted with German company Rudolf Hell to market adaptations of the Digiset photocomposition system as the Videocomp, and a Laser Color Scanner. The Videocomp was supported by a Spectra computer that ran the Page-1 and, later the Page-II and FileComp composition systems. RCA later sold the Videocomp rights to Information International Inc. (III).

RCA was a major proponent of the eight-track tape cartridge, which it launched in 1965. The eight-track cartridge initially had a huge and profitable impact on the consumer marketplace. Sales of the 8-track tape format peaked early as consumers increasingly favored the compact cassette tape format developed by Philips.

During the late 1960s and 1970s, RCA Corporation, as it was now formally known, ventured into other markets. Under Robert Sarnoff's leadership, RCA diversified far beyond electronics and communications, in a broader American corporate trend toward "conglomerates." The company acquired Hertz (rental cars), Banquet (frozen foods), Coronet (carpeting), Random House (publishing) and Gibson (greeting cards). The company struggled financially during this period.

Around 1980, RCA corporate strategy reported on moving manufacture of its television sets to Mexico. RCA was still profitable in 1983, when it switched manufacturing of its VHS VCRs from Panasonic to Hitachi.

Forays into new consumer electronics products lost money. The SelectaVision videodisc system, not to be confused with the same trademark that RCA applied to its VCRs, never developed the manufacturing volumes to substantially bring down its price, could not compete against cheaper, recordable videotape technology, and was abandoned in 1985 for a write-off of several hundred million dollars.

In 1981, Columbia sold its share in the home video division to RCA and its division was renamed outside of North America to "RCA/Columbia Pictures International Video" and the following year, it was renamed in North America to "RCA/Columbia Pictures Home Video".

In 1983, Arista Records owner Bertelsmann sold 50% of Arista to RCA. In 1985, Bertelsmann and RCA formed a joint venture called RCA/Ariola International which took over management of RCA Records.

Business and financial conditions led to RCA's takeover by GE in 1986, who subsequently broke up the company and sold various components onto other companies.