Vachon jumped to the World Wrestling Federation in 1984. While his age and lack of size did not make for a good mix in the emerging "Hulkamania" era, the now-face (fan favorite) Vachon put people in the seats and was usually included at WWF house shows (wrestling cards) in the Midwest and Quebec.
He appeared at the WWF pay-per-view In Your House 7, that was held in Omaha. He was sitting in the front row near ringside, when his artificial leg was ripped off by wrestler Diesel and used as a weapon by Shawn Michaels. In addition, he and longtime rival The Crusher made an appearance at the 1998 Over the Edge pay-per-view, in a segment where the two legends were mocked by Jerry "The King" Lawler, including Lawler trying to steal the artificial leg. Crusher and Mad Dog then punched Lawler out of the ring and shook hands.
On March 27, 2010, he was inducted into the 2010 WWE Hall of Fame.
On November 21, 2013, Vachon died.