Zbyszko debuted for the World Wide Wrestling Federation (WWWF) in 1973. He initially wrestled in the Pittsburgh area. He spent three years in the World Wide Wrestling Federation before traveling to California in 1975.
Zbyszko returned to the WWWF in 1976 and formed a tag team with Tony Garea, with whom he won the WWWF World Tag Team Championships on November 21, 1978 in Allentown, Pennsylvania. Their reign lasted until March 6, 1979, when they were defeated by the Valiant Brothers in Allentown.
Zbyszko feuded with Bugsy McGraw, Abdullah the Butcher and Superstar Billy Graham in addition to wrestling Killer Kowalski and Baron Mikel Scicluna.
At the end of the decade, Zbyszko became frustrated with his inability to shed his label as Bruno Sammartino's protégé. He challenged Sammartino to an exhibition match, claiming this was the only way he could step out of Sammartino's shadow. Sammartino eventually agreed to the match after Zbyszko threatened to retire if he was not granted the match. The trainer and pupil faced one another in Allentown on January 22, 1980, with Sammartino dominating the early stages of the match. After Sammartino threw him out of the ring, an irate Zbyszko seized a wooden chair and struck Sammartino, leaving him in a pool of blood in the middle of the ring and instantly turning Zbyszko into a reviled heel. After turning against Sammartino, Zbyszko was approached by the WWWF's "Unholy Trio" of managers (Fred Blassie, The Grand Wizard, and "Captain" Lou Albano), but he decided to continue wrestling without a manager. Sammartino and Zbyszko fought one another repeatedly in a lengthy feud that stretched throughout 1980. In the course of the feud, Zbyszko began referring to himself as "The New Living Legend" (a reference to Sammartino, who was often addressed as "The Living Legend"). The feud culminated in a steel cage match at Showdown at Shea at Shea Stadium in Flushing, New York on August 9, 1980 that saw Sammartino defeat Zbyszko in front of an audience of 36,295.
In March 1984, Zbyszko joined the American Wrestling Association. He engaged in a lengthy feud with Sgt. Slaughter, who defeated him on June 21, 1985 in Chicago, Illinois.
Zbyszko feuded with Nick Bockwinkel throughout 1986, losing to him in a Texas death match at Rage in a Cage on April 28, 1986. In the course of the feud, he also vied with Bockwinkel's ally Ray Stevens and Scott LeDoux. Zybszko lost to LeDoux in a boxing match at WrestleRock '86 on April 20, 1986 and fought him to a double count out at Battle by the Bay on June 28, 1986.
On May 2, 1987, Zbyszko helped Curt Hennig defeat Nick Bockwinkel for the AWA World Heavyweight Championship by handing him a roll of dimes to knock Bockwinkel out with. He was suspended "for life" by the AWA as a result of an assault on Bockwinkel during Bockwinkel's rematch with Hennig in July 1987. As Bockwinkel retired shortly after the incident, Zbyszko began claiming to have retired both Bockwinkel and Bruno Sammartino.
Zbyszko took part in an eighteen-man battle royal in Saint Paul, Minnesota on February 7, 1989 to fill the vacant AWA World Heavyweight Championship. By stalling and avoiding confrontations with other wrestlers, Zbyszko was able to remain in the match until only two men remained: himself and Tom Zenk. The two men fought for several minutes. When Zenk went for a pin, referee Gary DeRusha inexplicably entered the ring to make the count. Zbyszko kicked out and the two continued in what now appeared to be a conventional wrestling match. DeRusha ended up taking a bump and was unable to make the three count when Zenk covered Zbyszko for the pin. As DeRusha slowly recovered, Zenk continued to dominate the match. As he attempted a flying body press, however, Zbyszko managed to catch him in mid-air and deliver a fallaway slam, throwing him over the top rope and to the ground below. Zbyszko was thus the new AWA World Heavyweight Champion.
Early in his title reign, Zbyszko would feud with Wahoo McDaniel and Sgt. Slaughter. He would face Greg Gagne on June 23, 1989 at War in the Windy City, and David Sammartino, who he defeated at the Tri-State Winter Challenge on January 27, 1990. He then began feuding with Mr. Saito, who defeated him for the AWA World Heavyweight Championship on February 10, 1990 at Super Fight in Tokyo Dome during a tour of Japan. Zbyszko regained the title at SuperClash 4 on April 8, 1990, in Saint Paul and successfully defended it against The Trooper, Brad Rheingans, and Nikita Koloff (who he defeated on May 5, 1990 at Twin Wars '90) toward the end of his reign. He was stripped of the title after leaving the AWA for World Championship Wrestling on December 12, 1990.
In December 1990, Zbyszko joined WCW. Zbyszko initially teamed with Terrence Taylor, a member of The York Foundation, but was not recruited to the stable. Zbyszko was paired with Arn Anderson as the Enforcers in the late summer of 1991. After Scott Steiner, one-half of the World Tag Team Champions, was injured, the titles were vacated on July 18, 1991, and placed on the line in an eight-man tag team tournament. The tournament finals were held on September 5, 1991 at Clash of the Champions XVI: Fall Brawl and pitted the Enforcers against Rick Steiner and Bill Kazmaier. At the outset of the event, the Enforcers struck Kazmaier with a weight during a weightlifting demonstration, injuring his ribs. This enabled them to defeat Steiner and Kazmaier for the titles in the main event.
At Halloween Havoc, The Enforcers began feuding with Barry Windham and Dustin Rhodes, and broke Windham's hand by slamming the door of his car on his hand. Following this act, Zbyszko gave himself the sobriquet the "Cruncher". Windham was replaced by Ricky Steamboat, and at Clash of the Champions XVII on November 19, 1991 in Savannah, Georgia, the Enforcers lost the titles to Steamboat and Rhodes.
In December 1991, the Enforcers joined Paul E. Dangerously's Dangerous Alliance, which also included Rick Rude, "Stunning" Steve Austin, Bobby Eaton and Madusa. They feuded with Ricky Steamboat, Dustin Rhodes, Barry Windham, Nikita Koloff, Sting and the WCW World Heavyweight Champion Ron Simmons. On May 17, 1992 at WrestleWar 1992: WarGames, the Dangerous Alliance lost a WarGames match to their rivals after Zbyszko accidentally hit Eaton in the arm with the turnbuckle that he had dismantled, forcing Eaton to submit as a result of the pain. As a result of his blunder, Zbyszko was fired from the stable by Dangerously, turning him into a face for the first time since 1980. He briefly feuded with Austin and Eaton before retiring from full-time competition to become a color commentator. One of his first appearances as a commentator occurred at Starrcade alongside of Missy Hyatt. As a commentator, Zbyszko began referring to himself simply as "The Living Legend", as many WCW fans were unfamiliar with his feud with Bruno Sammartino. He also hosted an interview segment, "Larry Z's Legends" on WCW television which only lasted a few weeks.
In March 1994, Zbyszko began hosting WCW Pro, alongside Dusty Rhodes and Gordon Solie. Shortly thereafter, Lord Steven Regal began harassing Zbyszko, prompting him to return to the ring. On May 2, 1994 in Atlanta, Zbyszko defeated Regal for the WCW World Television Championship. He held the title until June 23, 1994 when Regal regained the belt in Charleston, South Carolina.
In 1996, Zbyszko was promoted to the WCW Monday Nitro broadcast team, where he announced during the first hour with Tony Schiavone. In 1997, he was antagonized by New World Order (nWo) member Scott Hall, but Hall opted not to face Zbyszko. Zbyszko remained in the broadcast booth for most of 1997, occasionally refereeing matches involving Hall and the nWo. On October 13, 1997, Zbyszko got involved in a WCW Tag Team Championship match between the Steiner Brothers and Scott Hall and Syxx (subbing for an injured Kevin Nash) and counted the ensuing fall for the Steiner Brothers who became the champions. This reign was official despite Zbyszko not being an official referee, a role he previously played in Scott Hall's match against Lex Luger at Halloween Havoc. On December 28, 1997 at StarrCade, Zbyszko returned to the ring for a match against Eric Bischoff for control of WCW Monday Nitro with Bret Hart acting as special referee. Hart ensured that the nWo did not interfere, and Zbyszko won the match, regaining control of Nitro for WCW. He continued to feud with Hall and his lackey, Louie Spicolli, culminating in a match between Zbyszko and Hall at Souled Out on January 24, 1998. Zbyszko won the match by disqualification after Dusty Rhodes betrayed him, joining the nWo.
Zbyszko went back to commentating, becoming part of the main WCW Thunder announce team in April along with Mike Tenay, leaving WCW Nitro. On December 6, 1999, when he faced Curt Hennig in a retirement match on Nitro and lost. He returned in January 2000 as a member of the Old Age Outlaws with Terry Funk, Arn Anderson and Paul Orndorff to feud with the revived nWo, then returned to commentary in February until he was released from his WCW contract in late 2000.
In April 2013, after attending the WWE Hall of Fame ceremony, he announced he had signed a WWE Legends contract along with recording interviews for the WWE Network and future DVD releases. On March 16, 2015, it was announced he would be inducted into the WWE Hall of Fame class of 2015. On March 28, he was inducted by his former mentor and rival Bruno Sammartino.