After leaving the WWWF, Studd became known as Chuck O'Connor, Captain USA, and The Masked Superstar II at certain points in the Mid-Atlantic. In 1978, Studd teamed with Ken Patera to win the Mid-Atlantic Tag Team Titles.
Studd also made occasional trips to Canada to wrestle in Emile Duprée's Atlantic Grand Prix Wrestling.
On May 25, 1980, Masked Superstar II was unmasked after a match with Blackjack Mulligan in Toronto. After this, Studd was brought into Florida by J.J. Dillon and feuded with Dusty Rhodes, Barry Windham, (the son of Blackjack Mulligan), and Sweet Brown Sugar.
Studd, who was a heel at this point, had a gimmick of bringing a stretcher to the ring as he would beat his opponents so badly that they'd be taken out on the stretcher.
Early on in 1982, Studd gained several unsuccessful title shots at the NWA World Heavyweight Championship, which was held by "The Nature Boy" Ric Flair at the time. Studd jumped to the World Wrestling Federation and became a top challenger for the WWF World Championship, which was held by Hulk Hogan. Studd (now managed by Bobby "The Brain" Heenan) also became involved in a legendary feud with André the Giant. Studd taunted André by proclaiming himself the true giant of professional wrestling and offering $15,000 to anyone who could bodyslam him. This led to a televised tag team match featuring Studd and fellow Heenan Family member Ken Patera against André the Giant and S.D. Jones. The match ended by disqualification after persistent rulebreaking by Studd and Patera, who attacked André afterwards and cut his hair. The André/Studd feud reached its high point at the first WrestleMania, when Studd and André had a $15,000 bodyslam challenge match, which André won. The highlight of André bodyslamming Studd to win the match is one of the most iconic images in wrestling history.
After WrestleMania, Studd formed an alliance with the 468 lb (212 kg) King Kong Bundy. The two attacked André at a WWF house show in the summer of 1985. Studd/Bundy and André continued to feud for the rest of that year and into 1986. Studd participated in the well-publicized 20 man over-the-top battle royal that took place at WrestleMania 2. The battle royale also featured stars from the National Football league. Although André the Giant was also in the battle royale, Studd set his focus on eliminating William "The Refrigerator" Perry, who was fresh from a Super Bowl victory that year. Studd successfully eliminated Perry during the match, only to have Perry to eliminate Studd while the two were shaking hands. André went on to win the battle royale.
After the André feud died down, the team of Studd & Bundy feuded with other established WWF tag teams including The Islanders and the WWF Tag Team Champions, The British Bulldogs. Studd & Bundy faced the Bulldogs for the Tag Team Titles on WWF Championship Wrestling, but they were unsuccessful in winning the match. Studd & Bundy then began arguing in the ring after the match, which seemed to indicate that a feud between the two was forthcoming. However, that would not be the case, and Studd & Bundy continued teaming up regularly for several more months. Studd's last match came on an episode of WWF Superstars (airing 11-15-86), where he teamed with Bundy to defeat The Machines.
After retiring for almost 3 years, Studd announced his return to the WWF on the Brother Love Show in late 1988. An elated Bobby Heenan appeared on the set to welcome Studd back to the Heenan family. Studd however rejected the offer and ran Heenan off the Brother Love set (thus turning face). Studd went on to feud with several members of the Heenan family, including his arch-nemesis André the Giant who had turned heel during Studd's absence. Studd won the 1989 Royal Rumble, which many consider to be the crowning achievement in his WWF career. Studd then served as a special guest referee in the match between Jake "The Snake" Roberts and André the Giant at WrestleMania V. Studd quit the WWF on June 6 1989.
Minton died from liver cancer and Hodgkin's disease on March 20, 1995. He is survived by his son John Minton, Jr., who accepted his plaque upon his posthumous induction to the WWE Hall of Fame in 2004. Minton, Jr. also participated in the fourth season of WWE Tough Enough.