Also known by his stage name The Anvil, Jim was part of the Hart Foundation tag team with his brother-in-law Bret Hart.
The American wrestler was also father to Natalya, a WWE Women’s and Divas champion who says her dad was “always a fighter”.
The WWE did not share a cause for Jim’s death, but paid tribute to him on its Monday night show and urged Natalya to “stay strong”.
WWE legend Triple H led the tributes on Twitter, saying: “The only thing bigger than his on-screen character was his heart.”
Jim won two World Tag Team Championships while competing in the 1980s and 90s with Bret “The Hitman” Hart.
Bret said he was “stunned and saddened” by the news.
Jim’s daughter Natalya said she “can’t put into words” how difficult it is to “say goodbye to my dad”.
She also thanked fans for messages of support. (Courtesy BBC)