In late 1984, Jim first appeared in the WWF as a wrestling fan known as "Big Jim" who routinely sat in the front row of live events and who eventually decided to try his hand at wrestling himself. After appearing as a guest on Piper's Pit, Rowdy Roddy Piper offered his services to train him, though he eventually chose to be "trained"' by WWF Heavyweight Champion Hulk Hogan instead of the heel Piper. A series of vignettes were aired on WWF's TV programming in the early weeks of 1985, showing Hogan training Jim and providing him with his first set of wrestling boots. This introduced the character of Hillbilly Jim; a simple-minded, shaggy-bearded Appalachian hillbilly clad in bib overalls, and hailing from Mud Lick, Kentucky. Hillbilly Jim appeared in a few tag team matches with friend Hulk Hogan, and had his first high-profile singles match at The War to Settle the Score event on February 18, 1985 in which he defeated Rene Goulet. However, Jim was sidelined by an injury a few days later. At a show in San Diego, he appeared in Hogan's corner in a match between Hogan and Brutus Beefcake. While chasing Beefcake's manager Johnny V around ringside, Jim slipped on a wet spot and injured his knee. To help fill in the six months during his recovery, similarly-dressed "family" members Uncle Elmer, Cousin Luke, and Cousin Junior were introduced for Jim to accompany to ringside as a manager.
When his in-ring career resumed, Jim often either tag teamed with his family, or fellow big man André the Giant. He was traditionally matched up against the WWF's monster heels of the era, such as Big John Studd and King Kong Bundy. He also had a short feud with Mr. Fuji, and wrestled him in a series of tuxedo matches in late 1986. Hillbilly Jim was generally kept as a "fun" character, rarely getting involved in any serious storylines. His theme music was a folksy barn dance tune called "Don't Go Messin' With a Country Boy", which Jim danced along to with his partners, the ring announcer and/or children from the crowd while the audience clapped along.
His first WrestleMania appearance was at WrestleMania 2 as part of the open invitational battle royal. His next WrestleMania appearance was a novelty match at WrestleMania III involving King Kong Bundy and midget wrestlers. At Survivor Series '88, Jim teamed with his old mentor Hulk Hogan along with Randy Savage, Hercules and Koko B. Ware to defeat the team of Big Boss Man, Akeem, Ted DiBiase, King Haku and The Red Rooster. Though Jim was eliminated by Akeem, Hogan and Savage would go on to survive and win the match.
Hillbilly Jim also worked as a fill-in for wrestlers who did not appear or who had left the company. John Studd had departed the WWF while in the midst of a major feud with Andre the Giant and Jim was called upon to fill Studd's role. On June 10, 1989 at the Nassau Coliseum Jim scored a huge upset over Andre the Giant defeating him by disqualification.
Hillbilly Jim continued to appear regularly in WWF matches until the summer of 1990. His last high-profile match with the WWF was during the April 28, 1990 (taped April 23, 1990) edition of Saturday Night's Main Event XXVI, in which he lost to Earthquake in a squash match that lasted just under 2 minutes. His final match was on August 31, 1990 against Black Bart in Cedar Rapids, IA.
In 1992, Hillbilly Jim returned to the WWF as one of the final hosts of WWF Prime Time Wrestling alongside Vince McMahon, Jim Duggan, Bobby Heenan, Mr. Perfect, Sgt. Slaughter and many more until the final episode of Prime Time Wrestling in January 1993.
He returned in December 1995 as a guest referee and a month later became manager of Henry O. and Phineas I. Godwinn, "cousins" who were pig farmers, leading them to the WWF Tag Team Championship. After the Godwinns turned heel in the spring of 1997, Hillbilly Jim was no longer needed as their manager. Jim later worked as a road agent and participated in the "Gimmick Battle Royal" in 2001 at WrestleMania X-Seven, where he eliminated Jim Cornette and Sgt. Slaughter, but was last eliminated himself by The Iron Sheik.
He was the official WWE legend host of the highly successful WrestleMania Axxess tour for WrestleMania XX, WrestleMania 21, WrestleMania 22, and WrestleMania 23 in major malls across the US.
On April 10, 2012, Hillbilly Jim made an appearance on WWE SmackDown: Blast from the Past. He also appeared in WWE Legends' House, which aired on the WWE Network in 2014.
Hillbilly Jim was officially inducted into the WWE Hall of Fame on April 6, 2018.