Creditors hold $2.9 million in unsecured claims against Gardner, including $2.8 million by the West Coast Lending Group of Salt Lake City.
The case has been assigned to U.S. Bankruptcy Court Judge R. Kimball Mosier.
Calls to Gardner were not immediately returned Tuesday. Chad Shattuck, an attorney with Tycksen & Shattuck in Draper, is listed in court documents as representing Gardner. He declined to comment.
Gardner's financial trouble is the latest in a series of unhappy events involving the 41-year-old ex-Olympian, who was born in Afton, Wyo.
In 2002, Gardner was stranded in the Wyoming wilderness while snowmobiling. He was rescued after 18 hours and suffered hypothermia and severe frostbite, which led to the amputation of one toe.
In 2007, Gardner and two others survived a plane crash at Lake Powell. It took the victims an hour to swim to shore, where they spent the night before being rescued. No one suffered life-threatening injuries.
Last year, Gardner weighed 474 pounds and appeared on the reality television show "The Biggest Loser." He wanted to lose enough weight to make a comeback at the London Olympics, but he was stopped by doctors from continuing his attempt to reduce his weight.
On Oct. 27, an established Salt Lake City-based appraisal and marketing company will host an auction on its website involving Gardner's property.
According to Erkelens & Olson Sales and Auctions, "Vehicles, furniture, guns, four-wheelers and many items owned by a famous Olympic wrestler" will be sold.
Some of Gardner's most valuable belongings will be available to buyers, including a Porsche, a Harley-Davidson motorcycle and 40 watches.
"We get involved in these cases when the [bankruptcy] trustee calls us," said Rob Olson, owner of Erkelens and Olson. "Then we mobilize to get the items picked up and brought back to our business. ... We do this type of thing quite a bit. A lot of times, we're the trustee's eyes and ears."
Olson expects the Gardner auction will be well-attended.
"If it's a well-known person a celebrity it seems to pique people's interest," he said. "It seems people want to know what [famous] people have. They tend to come and look around."
Tribune reporter Steve Oberbeck contributed to this story.