Shortly afterward, a new company called Sunbeam Television Corporation bought the station for $3.4 million and assumed ownership of channel 7 on December 19, 1962. Upon the change in ownership, Sunbeam retained the WCKT call letters and claimed the Cox/Knight station's history as its own. Sunbeam was a partnership between Miami Beach-based real estate developer Sydney Ansin, and his son Edmund Ansin. The younger Ansin succeeded his father as president of Sunbeam Television in 1971. The station began using its own version of the circle 7 logo (which is moderately similar to the version originally created for ABC's owned-and-operated stations, but with the "7" not connected to the circle and being somewhat shaped differently) in the mid-1970s. On June 7, 1983, the station's callsign was changed to the current WSVN, after those call letters were acquired from a PBS satellite member station in Norton, Virginia (which subsequently became WSBN-TV; it has since gone off the air).
NBC experienced a resurgence in the second half of the 1980s, resulting in it becoming the top-rated U.S. television network–a status helped by the crime drama Miami Vice, which was set and filmed in and around Miami. The Miami–Fort Lauderdale area was also developing into one of the largest media markets in the United States. But NBC's standing in the area was deemed unsatisfactory, as WSVN was the third-ranked affiliate in the market (behind WTVJ and WPLG). As a result, NBC decided that it needed to acquire its own station in the growing South Florida metropolitan area. The network got its chance at doing so in the late 1980s, when Kohlberg Kravis Roberts put WTVJ on the market. NBC's then-corporate parent General Electric purchased that station in 1987, but WTVJ's affiliation contract with CBS was not set to expire until December 1988. CBS was willing to let WTVJ out of its contract one year early. However, Ed Ansin was not interested in letting NBC out of its affiliation agreement with WSVN, which also expired at the same time; Ansin even made an unsuccessful petition to the FCC to stop NBC's purchase of WTVJ. He wanted channel 7 to air NBC's strong fall 1988 lineup, which included NBC Sports' coverage of Major League Baseball's World Series and the Summer Olympics, along with most Miami Dolphins games as part of NBC's National Football League package. As a result, NBC was forced to run WTVJ as a CBS affiliate for more than a year, with all of the NBC shows that were preempted by WSVN airing on WTVJ instead. This situation did not sit well with either network. Ansin made an offer to take the CBS affiliation, but CBS turned the offer down. Instead, CBS bought Miami's longtime independent station and original Fox affiliate, WCIX channel 6, even though that station had an inadequate signal in Broward County (WCIX's transmitter was located in Homestead, farther southwest than those of other Miami area stations, to avoid signal interference with WCPX-TV (now WKMG-TV) in Orlando and WPTV). In May 1988, Ed Ansin filed an antitrust lawsuit against General Electric/NBC and CBS, one week after he had claimed that CBS backed out of contract negotiations to affiliate with WSVN. With WCIX planning to switch to CBS at the start of 1989, Fox began negotiations with other area stations to carry its programming. It ultimately reached an agreement with Sunbeam Television to affiliate with channel 7.
On January 1, 1989, South Florida's first network affiliation switch occurred, with NBC moving to WTVJ full-time, WCIX switching from Fox to CBS, and WSVN taking the Fox affiliation. Channel 7 had far fewer network shows to preempt as a result, as Fox only ran prime time programming on weekends at the time and would not air an entire week's worth of programming until 1993. As a result, WSVN was for essential intents and purposes programmed as a de facto independent station (even referring to itself as such in promotions regarding the switch, despite still being affiliated with a network). Until Fox began airing programming every weeknight, WSVN aired a movie in prime time at 8:00 p.m. on nights where network programming was not scheduled to air. WSVN's affiliation with Fox could be seen as a major coup for the fledgling network, as WSVN had been a longtime NBC affiliate and Fox was pleased to affiliate with a station that had been with a "Big Three" network for years. At the time, WSVN was one of the largest heritage "Big Three" stations to join Fox. The combination of WSVN not following a similar pattern to other Fox affiliates at the time (which focused more on syndicated programming and movies, than news), and WCIX becoming a "Big Three" affiliate had also led then-struggling independent WDZL (channel 39, now CW affiliate WSFL-TV) to rise to a higher profile, as WDZL had picked up many shows that were formerly seen on WCIX (now WFOR-TV on channel 4). WSVN, meanwhile, picked up some of WCIX's movie packages, as well as a couple of cartoons that it aired on Saturday and Sunday mornings. WSVN archive betacam newstape at the Florida Moving Image Archive. Instead of acquiring a large amount of off-network sitcoms and cartoons, WSVN opted to pour most of its resources into its news department and took on a news-intensive format—expanding its newscasts to seven hours on weekdays—a move that was pilloried at the time since its newscasts had consistently finished well behind WTVJ and WPLG in the ratings. Because of this, the station had a higher local newscast output than the rest of Fox's stations did at the time of the switch; when WSVN became a Fox affiliate, only a small number of Fox stations ran local newscasts, which were largely limited to late prime time slots (as of 2014, about ¾ of Fox's stations have morning newscasts, but only about one-third of its owned-and-operated stations and affiliates carry newscasts in either the midday or late afternoon/early evening time periods). In addition to newscasts, WSVN began to air a lot of first-run syndicated talk shows, court shows, and off-network drama series. As Fox lacked a national evening newscast (a situation which continues to this day), the station also ran a half-hour late afternoon simulcast of CNN Headline News during the early and mid-1990s. The station ran some cartoons on weekend mornings as well. In the early 1990s, the station added a few off-network sitcoms to its schedule such as Designing Women, The Golden Girls, and Empty Nest (the latter two being set in Miami).
As a Fox affiliate, the station brands itself as "WSVN 7", rather than "Fox 7" under Fox's branding guidelines for its owned-and-operated stations and affiliates (Boston sister station WHDH formerly used its affiliated network's name in its branding as "7 NBC" until it became an independent station in January 2017, although NBC is not as strict with station branding as Fox is), and is one of a handful of Fox affiliates that omit network references entirely from their branding. However, Fox News Channel refers to the station as "Fox 7" when carrying WSVN's coverage of breaking news stories from South Florida; until its website was remodeled in late 2009, the Fox logo also occasionally appeared in a rolling marquee alongside the station's "circle 7" logo on the top left hand corner of the site. At the time of the 1989 switch, the network's owned-and-operated stations and certain affiliates were the only Fox stations to use full network references, while other stations—like original Miami affiliate WCIX used limited to no references to Fox in their branding. Miami–Fort Lauderdale is one of three U.S. television markets in which the Fox affiliation had moved from one VHF station to another (the others being Honolulu, Hawaii, if stations not operating as satellites are counted, as Fox charter affiliate KHNL (channel 13) and NBC affiliate KHON-TV (channel 2) swapped affiliations on January 1, 1996, and Boise, Idaho, when CW affiliate KNIN-TV (channel 9) took the Fox affiliation from charter affiliate KTRV (channel 12) on September 1, 2011) and the only known instance of a longtime "Big Three" affiliate switching to Fox prior to its 1994 affiliation agreement with New World Communications and the affiliation transactions that resulted from the deal. On January 14, 2012, WSVN and Boston sister stations WHDH and WLVI were pulled from DirecTV after negotiations with Sunbeam Television on a new carriage contract broke down due to a proposal to increase retransmission fees paid to the company by a reported 300%. In response, a Facebook page called "Boycott WSVN" was started to pressure businesses to pull their advertising from the station. However, WSVN did allow DirecTV customers to view the NFC championship game and an episode of American Idol that aired immediately after the game while negotiations were still ongoing. Sunbeam and DirecTV reached a new carriage deal on January 26, 2012, ending the blackout. Since Fox acquired National Hot Rod Association (NHRA) broadcast rights in 2016, WSVN has constantly been the target of viewer and NHRA complaints, the station preempts Fox NHRA in favor of infomercials, resulting in the NHRA sending a formal complaint on their website. This usually amounts to four NHRA events a season, including the U.S. Nationals. The station often preempts live coverage of the NHRA and German Bundesliga soccer matches to after the late news in order to retain paid programming revenue for those afternoon timeslots that Fox uses to carry prestigious sporting events. On September 27, 2017, three workers were killed after a crane collapsed off the side of WSVN's television tower. The tower, shared with WPLG, was having to install a new transmitter for WSVN as part of the mandated FCC spectrum repack.