[7] WBZ is the designated Primary Entry Point (PEP) for the Emergency Alert System (EAS) in Massachusetts and New Hampshire.

WBZ is a clear-channel station (officially classified as Class A), with a transmitter power output of 50,000 watts, and employing a directional antenna that sends a majority of its signal westward.

[8][9][10][11][12] WBZ was granted its first license by the United States Department of Commerce on September 15, 1921, and was originally located in Springfield, Massachusetts, before moving to Boston in 1931.

WBZ is heavily involved in charitable work, including its annual Christmastime fund drive for the Boston Children's Hospital, which it does along with TV station WBZ-TV.

In November 1920, the Westinghouse Electric & Manufacturing Company established its first broadcasting station, KDKA, located in its plant in East Pittsburgh, Pennsylvania.

(A prime example was the American Radio & Research Corporation's experimental station, 1XE in Medford Hillside, Massachusetts, near Boston, which was relicensed in early 1922 as WGI.)

[20] Despite being housed in Springfield's top hotel, the station's location in a mid-sized city rendered it somewhat difficult to attract top-flight artists.

[20][31] Efforts were soon made to change WBZA to a synchronous repeater, transmitting on the same frequency as WBZ, 900 kHz, but the process proved difficult, as the two transmitters often interfered with each other, even in Boston.

For nearly a year, while the technology was being perfected, WBZA shifted between the two transmitting frequencies, before finally going to full-time synchronous operation in June 1926.

[20] On November 11, 1928, under the provisions of the Federal Radio Commission's (FRC) General Order 40, WBZ and WBZA were assigned exclusive national use of a "clear channel" frequency, 990 kHz.

By 1931, Westinghouse had concluded that WBZ's primary market was Boston, so on February 21 the station began using a new transmitter site located at Millis, Massachusetts.

[46] Under the provisions of the North American Regional Broadcasting Agreement, on March 29, 1941, WBZ's "clear channel" assignment was shifted to its present frequency, 1030 kHz.

Westinghouse built new studios at 1170 Soldiers Field Road in the Allston section of Boston to house both the radio and television stations, with the new facility opening on June 17 of that year.

[53] At the outset, WBZ's full-service radio format leaned toward middle of the road music, but also featuring an increasing amount of rock and roll.

[54] The combination of hit music, popular hosts (such as evening DJ "Juicy Brucie" Bradley who did the daily top-10 countdown), powerful signal, and top-notch news coverage, made WBZ the dominant radio station in the market.

[55][56] WBZ re-established an FM station on December 15, 1957, transmitting from the brand new WBZ-TV tower in Needham, operating at 106.7 MHz.

The station remained in mono through this period, but beginning on December 31, 1971, an automated top 40 format was launched in stereo, apparently in an attempt to blunt the popularity of WRKO (680 AM).

The towers continued to stand atop the former Westinghouse plant in East Springfield for five more decades, until their removal on November 5, 2011, to accommodate redevelopment at the site of the factory.

[63] Also heard were Jerry Williams in the evenings and Larry Glick's overnight show (the latter two held the same popular shifts at WMEX years earlier).

[64] For much of its time as a full-service AC, WBZ used the slogan "The Spirit of New England" (made famous by a 1988 JAM Creative Productions jingle package of the same name).

[64] Calling All Sports was also dropped in favor of an early evening talk show, hosted at various points by David Finnegan, Lou Marcel, and Peter Meade.

[52] In the 1980s, WBZ began to cut back on its music programming; for instance, an expanded afternoon news block was launched on December 2, 1985.

WBZ continued its full-service AC format—by this point featuring four songs an hour[75]—until January 1991, when Gulf War coverage led the station to stop playing music on a regular basis and pivot to news and talk full-time,[54][76] joining WRKO and WHDH (850 AM, now WEEI) in the format.

[109] Shortly afterward, David Brudnoy gave up the 10 p.m.-12 a.m. portion of his show;[108] this timeslot was given to Lowell Sun columnist and former WLLH (1400 AM) host Paul Sullivan.

[131] While Jordan Rich retained his weekend overnight show, the 2–5 a.m. portion of the program began to be simulcast on sister station WCCO in Minneapolis–Saint Paul.

[133] The Bruins once again left WBZ following the 2008–09 season, after CBS Radio launched a third incarnation of WBZ-FM on 98.5 MHz as an all-sports station, which also took the Patriots from the former WBCN.

WBZ, along with fellow CBS Radio all-news stations WINS in New York City, KYW in Philadelphia, and WNEW-FM in Washington, D.C., added an affiliation with Westwood One News in 2014.

On February 2, 2017, CBS Radio announced it would merge with Entercom (which locally owned WEEI, WEEI-FM, WKAF, WRKO and WAAF); the sale would be conducted using a Reverse Morris Trust so that it would be tax-free.

On October 10, CBS Radio announced that as part of the process of obtaining regulatory approval of the merger, WBZ would be one of sixteen stations that would be divested by Entercom, along with sister stations WBZ-FM and WZLX, as well as WRKO and WKAF (WBMX, WODS, WEEI AM/FM and WAAF would be retained by Entercom, while WBZ-FM would be traded to Beasley Broadcast Group in exchange for WMJX).

To meet ownership limits set by the FCC, WKOX would be divested to the Ocean Stations Trust in preparation for a permanent buyer.