His fame as a footballer attracted the attention of wrestling star, Ed Lewis and promoters Toots Mondt and Billy Sandow, who prematurely pushed Munn as the next big star in the sport. Munn won the World title from Lewis in 1925, despite his limited wrestling and shooting ability. This backfired on Lewis and his camp, as Munn subsequently lost the Title to Stanislaus Zbyszko in a famous double-cross (shoot), as Zbyszko legitimately pinned Munn, despite agreeing to lose to him prior to the match. Munn, unable to defend himself against Zbyszko's holds, was beaten decisively. Munn held the title for a little over three months.
Munn went into retirement shortly afterwards, and spent some years in the oil business, before his death from kidney problems at the Fort Sam Houston base hospital in San Antonio, Texas on January 9, 1931. He was survived by his wife and a daughter, Mary Ann Munn.