Court records show Gardner owes a major creditor nearly $3 million while bringing in a household income of $37,392.
Gardner disputes the debt, saying he was defrauded by a business associate into co-signing a loan to develop a hot-spring resort in his hometown of Afton, Wyo., that "was nothing but a complete fraud."
Gardner said he lost $400,000 of his own money on the deal and the creditor is going after him while his former business partner is in federal prison for fraud.
"I got taken advantage of, and now I've got to pay the price," Gardner said late Tuesday. "I'm trying to make it right."
The creditor, WestCoast Lending Group Inc., didn't immediately return a phone message Tuesday from The Associated Press.
Gardner will offer his version in a deposition scheduled for Oct. 10, bankruptcy trustee David L. Miller said.
Less than three weeks later, the Salt Lake City auction house of Erkelens & Olson is set to sell off his most valuable belongings, including a Ford Excursion SUV, Harley-Davidson motorcycle, dozens of watches and knives, his wrestling shoes and autographed memorabilia.
Gardner's Olympic gold medal was on a seizure list for the auction but authorities couldn't find it and Gardner told them it had been stolen, Cache County Deputy Sheriff Brad Slater said Tuesday.
Deputies who raided Gardner's home in Wellsville on Aug. 15 also couldn't find a Jeep that was supposed to be seized, Slater said.
Gardner filed for bankruptcy protection Aug. 31 and said he's trying to stop the auction.
"I'm offering to buy the stuff back, but my money is tied up in a lot of businesses," he said.
He added, "I don't have all this money people think Olympic athletes have."
His bankruptcy lawyer, Chad Shattuck, declined to comment.
Gardner rose to fame at the 2000 Sydney Olympics by toppling Russian Alexander Karelin, who had been unbeaten for 13 years. A year later, Gardner won the world title.
Later, Gardner nearly died after a night stranded in the Wyoming wilderness, and he survived a motorcycle accident and a plane crash.
Last year, he weighed in at 474 pounds on the reality TV show "The Biggest Loser" before losing weight in a failed attempt to qualify for the London Olympics that friends say taxed his health.
Gardner moved to Wellsville years ago and opened a gymnasium in nearby Logan that now operates under another name. He said he had $1 million invested in the gym.