Windham (and Mike Rotunda) were signed by World Wrestling Federation (WWF) in October 1984. They debuted in WWF as babyfaces on the November 17, 1984 edition of Maple Leaf Wrestling defeating Mohammed Saad and Bobby Bass. Their tag team was named "U.S. Express". They quickly made impact in WWF's tag team division as they beat North South Connection (Dick Murdoch and Adrian Adonis) for their first WWF Tag Team Championship on January 21, 1985, at a house show in Hartford, CT. At the first-ever WrestleMania, US Express dropped the titles to Iron Sheik and Nikolai Volkoff. On the July 13 edition of Championship Wrestling, they beat Sheik and Volkoff for their second and final WWF Tag Team Championship, which they lost to Dream Team (Greg Valentine and Brutus Beefcake) in Philadelphia at The Spectrum on August 24.
Windham returned to the WWF in June 1989 as the Widowmaker. Despite the nickname, Windham did not change his image much, portraying a heel cowboy type character. He went undefeated for four months and was to have been on Randy Savage's Survivor Series team, but was replaced by the Canadian Earthquake as Windham left the company in October due to undisclosed personal reasons.
Windham would again return to the WWF in late 1996, this time as "The Stalker", wearing camouflage face paint as well as being billed from "The Environment". Windham's success with this gimmick was hampered by last minute changes. Windham cut promos as a heel, displaying The Stalker as a deranged and dangerous former military man and was scheduled to start a feud with Marc Mero. Mero, however, refused to agree to the planned storyline that would have been kick started by The Stalker stalking Sable and (kayfabe) cutting her throat. Following Mero's rejection of this plot point their whole program was scrapped and Stalker was introduced with little fanfare as a babyface. For a short time, he renewed his feud with Goldust. In Windham's only pay-per-view appearance with this gimmick, he was eliminated from a Survivor Series match at Survivor Series 1996 by Goldust. Stalker's teammate, however, the debuting Rocky Maivia, became the sole survivor of the match.
Windham later formed The New Blackjacks with Justin "Hawk" Bradshaw in 1997. Windham dyed his hair black and waxed his moustache. The tag team was a tribute to the original Blackjacks (Mulligan and Lanza). The team had opportunities for the World Tag Titles but no success. That team didn't last long, as Windham turned on Bradshaw to join Jim Cornette's faction in 1998. The angle was scrapped months later, and Windham left again.
He returned on the "WrestleMania Rewind" episode of Raw with Mike Rotunda on March 10, 2008 in a rematch from the first WrestleMania.
Windham worked as a producer for WWE. In 2007, he appeared on the Ric Flair and the Four Horsemen DVD. Barry was also seen during the 2007 WWE Hall of Fame broadcast, sitting next to former partner John "Bradshaw" Layfield. On December 31, 2008, he was released by the WWE.
He was inducted into the Hall Of Fame in 2012 as a member of the Four Horsemen.