Hennig returned to the WWF in the fall of 1988 as "Mr. Perfect" Curt Hennig, an arrogant braggart villain who claimed to be able to accomplish difficult tasks "perfectly." In the weeks before his debut, Hennig shot several promos to get his persona of being superior in athletics or anything else he did. These clips showed him hitting half-court, three-point, and no-look basketball shots, bowling score of 300, running the table in billiards, throwing then catching his own Hail Mary football pass, sinking a long golf putt, hitting home runs and making bulls-eyes in darts. Stars of various major league sports, including Wade Boggs, Steve Jordan, and Mike Modano, co-starred with Hennig in these vignettes.
Hennig went undefeated for over a year, beating mid-card wrestlers including The Blue Blazer, The Red Rooster and Jimmy Snuka. During 1989, use of Hennig's real name was phased out, save for occasional references to his family history, and he was billed exclusively as "Mr. Perfect". Although undefeated on television, Perfect fought Bret "Hit Man" Hart to a draw at several house shows. Later in 1989, Perfect began appearing with Lanny Poffo, who had turned heel earlier in the year and began competing as "The Genius," an arrogant scholar. That fall, Perfect began feuding with Hulk Hogan over the WWF Championship. In the first nationally televised contest of a rivalry that would span Hennigs's WWF and WCW careers, Perfect defeated Bret Hart on the November 6, 1989 edition of Prime Time Wrestling, when he pulled Hart's tights during a roll-up, building momentum for an eventual meeting with Hogan. Their feud heated up when, after The Genius defeated Hogan by countout, Poffo and Perfect stole Hogan's title belt and destroyed it backstage. Although Hogan later pinned Hennig at several house shows, these were not taped and no reference was made to them on television. Perfect and Hogan were the last two men left in the 1990 Royal Rumble, with Hogan getting the victory. Perfect's first one-on-one loss on television was to Brutus "The Barber" Beefcake at WrestleMania VI at the Toronto Skydome, though a week earlier he was pinned by The Ultimate Warrior in a taped show at Madison Square Garden.
Enlisting Bobby Heenan as his new manager, Perfect went on to win the vacant Intercontinental Title in the final round of a tournament in April 1990 by defeating two-time Intercontinental Champion Tito Santana. He lost the belt to The Texas Tornado four months later at SummerSlam, but regained the title on November 19, 1990, thanks to interference from Ted DiBiase. This title win aired on the December 15, 1990 edition of WWF Superstars of Wrestling. Perfect faced the Big Boss Man at WrestleMania VII, where a disqualification loss meant that he retained his title. The following month he was the winner of a 20-man Battle Royal on Saturday Night's Main Event. Perfect held the Intercontinental Title until August 1991, when a broken tailbone and buldged discs forced him to drop the belt to Bret Hart at SummerSlam; In the month of May prior to this match, Heenan retired from managing, which led to "Coach" John Tolos becoming Mr. Perfect's new manager. This was short-lived, as Perfect had actually retired from the ring a couple months before SummerSlam, but he just returned for one match to drop the title to Hart.
After losing the Intercontinental Championship, Perfect spent the next year-plus, trying to recuperate from his injuries. While recovering, he acted as Ric Flair's "executive consultant" during Flair's two WWF Championship reigns. He also worked as a color commentator on WWF Superstars of Wrestling following Survivor Series 1991 until the Superstars before the next Survivor Series, acting as a suitable heel foil to Vince McMahon's play-by-play.
Perfect began a return to wrestling and a fan favorite turn when he had a falling-out with Ric Flair and Bobby Heenan (Flair's financial adviser) on the last Prime Time Wrestling before Survivor Series 1992 after Randy Savage asked Perfect to be his partner against Flair and Razor Ramon at the 1992 Survivor Series. After initially laughing off Savage's decision, Perfect was swayed by Savage's cajoling and by Heenan's comments that Perfect was not capable of wrestling on that level anymore and demanded that Perfect follow orders and do as he was told. Immediately afterward, Perfect turned towards the camera to accept Savage's proposal, much to the horror of Heenan, who then slapped Perfect across his face. An infuriated Perfect responded by grabbing Heenan by his tie and pouring a full pitcher of water over Heenan's head. Perfect then stated that he was "back" as Savage's partner at the Survivor Series, much to the delight of the Prime Time Wrestling cast of Hillbilly Jim, Jim Duggan, and Vince McMahon. Perfect returned to the ring at the Survivor Series and, despite some initial mistrust between them, he and Savage won the match by disqualification. Perfect later eliminated Flair from the 1993 Royal Rumble and defeated Flair the next night on Monday Night Raw in a "Loser Leaves the WWF Match". In reality, Flair gave his notice that he was going back to WCW shortly after Survivor Series and promised to put over Perfect before he left.
He then went on to feud with Lex Luger, whom Heenan introduced into the WWF at the Royal Rumble. Luger won their match at WrestleMania IX though both of Perfect's feet were clearly between the ropes. Afterwards, Perfect chased Luger backstage where he was jumped from behind by Luger's onscreen ally Shawn Michaels. This feud with Michaels led to an Intercontinental Title match at Summerslam 1993, which Perfect lost by countout due to interference from Michael's new bodyguard Diesel.
Perfect also competed in the 1993 King of the Ring tournament, losing in the semi-finals to eventual winner Bret Hart. He was then set to participate in the opening bout at 1993's Survivor Series, but due to the re-emergence of his back injuries, was replaced by "Macho Man" Randy Savage and apparently had left the company.
At WrestleMania X, Perfect was the special guest referee for the title match between Lex Luger and Yokozuna. Perfect disqualified Luger after Luger manhandled Perfect, who was tending to Yokozuna's stricken managers Jim Cornette and Mr. Fuji instead of counting the pin. Perfect was set to start another feud with Luger (this time with Perfect as the heel) following WrestleMania, but plans were changed when Hennig's back problems flared up again. He left the WWF in the spring of 1994.
Hennig took a year off to recover from a back injury. He returned in 1995 as a color commentator at the Survivor Series. The following weekend, Jerry Lawler announced Perfect as his replacement on WWF Superstars, his second stint as a color commentator on the show with McMahon, this time with Jim Ross added as the analyst. Later in 1996, McMahon left and Ross switched to the play-by-play role. Perfect also did color commentary with McMahon at the 1996 Royal Rumble and the 1996 SummerSlam with McMahon and Ross, and also at In Your House 10: Mind Games with Ross and McMahon, and in the video game WWF In Your House with McMahon. Mr. Perfect was once again called upon to serve as special referee for the WWF Championship match at 1996 King of the Ring between Shawn Michaels and the British Bulldog.
Perfect was initially going to make his wrestling comeback on Monday Night Raw in October 1996 against Hunter Hearst Helmsley but was attacked by Helmsley backstage just moments before their match. It appeared Helmsley's attack left Perfect injured and unable to compete. This all turned out to be a ruse for the purpose of suckering "Wildman" Marc Mero into defending his Intercontinental Championship against Helmsley. With help from Perfect, Helmsley won the Intercontinental Title from Mero, and Perfect was once again a heel. Perfect began to serve as a mentor to Helmsley and "hand picked" beautiful models to accompany Helmsley to the ring. Perfect disappeared from the WWF once again shortly before the 1996 Survivor Series.
During the build up for January's Royal Rumble, it was announced that Hennig would be returning as one of the 30 combatants. Hennig, again billed as "Mr. Perfect" (although his real name was widely acknowledged), entered the Royal Rumble at #25, and was one of the final three competitors before being eliminated by eventual winner Triple H. Perfect made a strong showing at the Rumble, hitting the Perfect-Plex on Kurt Angle and holding his own with the WWF's best at the time. His performance, along with the positive reaction of the Atlanta crowd, earned Hennig a full time contract with the WWF. Perfect appeared the next night on Raw in a match with The Big Valbowski. He then had short feuds with Stone Cold Steve Austin and Rob Van Dam before forming a tag team with Shawn Stasiak at house shows throughout March and April as well as a tag team on television with The Big Boss Man. Perfect was drafted to Raw during the first ever WWF Draft. However, Hennig was released from the company on May 5, 2002 due to a physical confrontation with Brock Lesnar.
On February 10, 2003, Hennig was found dead in a Florida hotel room at 44 years old.
Wade Boggs, who appeared in a vignette with Hennig and was a friend of his, inducted him into the WWE Hall of Fame on March 31, 2007. His wife, his four children, and his parents accepted the award on his behalf.