Monsoon first wrestled Bruno Sammartino for the WWWF World Championship on October 4, 1963, at Roosevelt Stadium, in Jersey City, NJ.
In 1963, the WWWF was the dominant wrestling promotion in the Northeast U.S. Marella formed a friendship with McMahon, and became a 1/6 shareholder in the WWWF, controlling bookings in several WWWF territories. He also became one of the promotion's top heels, feuding with popular babyface champion Bruno Sammartino in sellout arenas across the country. Despite his huge size, which was now in excess of 400 pounds, Monsoon had great agility and stamina, often wrestling Sammartino to one-hour time-limit draws.
Monsoon teamed up with Killer Kowalski with success. In November 1963, they defeated Skull Murphy and Brute Bernard to win the U.S. Tag Team Championship. The following month, the duo lost the belts to the Tolos Brothers (Chris and John) in Teaneck, New Jersey. Monsoon and Kowalski reunited in the late 1960s to defeat champion Bruno Sammartino and Victor Rivera 2 falls to 1 in Madison Square Garden in a main event, marking the first, and possibly only time, that Sammartino & Rivera lost as a tag team.
In 1969, Monsoon became a babyface, befriending his former arch-rival when Sammartino rescued him from an attack by Crazy Luke Graham. The stage was set for Monsoon to become a fan favorite of the 1970s and feud with top heels of the decade, including champion "Superstar" Billy Graham. He turned heel again in 1977 and feuded with André the Giant.
On June 16, 1980, a young and up-and-coming Hulk Hogan was booked to face him at Madison Square Garden. At the time, Hogan was a widely followed heel character, while Monsoon was still a babyface. However, in order to push the new talent, McMahon told Hulk Hogan to beat Monsoon in under a minute.
As the 1980s began, Monsoon's in-ring career wound down. On August 23, Monsoon put his career on the line in a match against Ken Patera. Monsoon lost the match and stayed true to his word, retiring several weeks later and returning just four times: wrestling a match in 1982 as a substitute for André the Giant, taking part in Big John Studd's "Body Slam Challenge" in 1983, a six-man tag team match at Madison Square Garden, and participating in a special "old timers" battle royal in 1987 which was won by Lou Thesz. The next phase of his career began, as the voice and backstage manager of WWF.
In the early 1980's, Vincent K. McMahon needed a new commentary team to head up his television programming, and installed Gorilla with the recently retired Jesse "The Body" Ventura as the new commentary team.
Monsoon and Ventura had great chemistry, with Ventura as the pro-heel color commentator and Monsoon as the pro-face "voice of reason." Gorilla and Ventura called five of the first six WrestleManias together (the notable exception was WrestleMania 2, where Monsoon commentated on the Chicago portion of the event with Gene Okerlund and Cathy Lee Crosby while Ventura commentated on the Los Angeles portion with Lord Alfred Hayes and Elvira). The Ventura/Monsoon duo of heel and babyface were the original broadcast duo that everyone tried to emulate, especially Ventura's charismatic pro-heel character. When Ventura left the WWF in 1990, Monsoon was paired with villainous manager Bobby "The Brain" Heenan, another duo that subsequent wrestling commentary teams have often tried to emulate. The two also formed a real-life friendship which Heenan often recalls fondly.
Monsoon called the first eight WrestleManias from 1985-1992. Monsoon was the lead commentator on the syndicated show, WWF All Star Wrestling, its successor WWF Wrestling Challenge, and the USA Network weekend show, WWF All American Wrestling, as well as hosting the WWF weeknight show, WWF Prime Time Wrestling.
Monsoon stepped down as the WWF's lead commentator at WrestleMania IX. He commentated with Jim Ross on WWF Radio for the broadcasts of SummerSlam 1993, Survivor Series 1993 and Royal Rumble 1994. He returned to the television broadcast team to call the King of the Ring 1994 with Randy Savage. Monsoon's last pay-per-view as a commentator was calling the 1994 Survivor Series with Vince McMahon. Monsoon remained in his backstage role and appeared on-air frequently, becoming the storyline WWF President in the summer of 1995 (replacing Jack Tunney). The WWF President's role was to arbitrate disputes between wrestlers and make matches, similar to the current WWE general managers. It was during this time that Roddy Piper became interim WWF President until WrestleMania XII, when Monsoon assumed the position again. Health concerns forced him to relinquish this role during the summer of 1997. Instead of naming a replacement, the WWF decided to retire the role of "President" and introduced Sgt. Slaughter as the new WWF Commissioner in August 1997. Monsoon's health deteriorated from there. In late 1998, Gorilla returned briefly to call the international version of WWF Superstars. Sometime in early 1999, Monsoon appeared in a WWF Attitude commercial featuring Freddie Blassie, Ernie Ladd, Pat Patterson and Killer Kowalski. His final appearance on WWF television before his death was as one of the three judges for a Brawl for All contest between Bart Gunn and Butterbean at WrestleMania XV. Because of his frail appearance and rapidly declining health, the camera only focused on Monsoon during his introduction as a judge, to which he received a standing ovation.
He died on October 6, 1999.