The free agent running back is in a dispute with Nissan's financing arm. Nissan says McAllister owes more than $6.6 million and nearly $300,000 in interest.
The company says McAllister defaulted on a deal, then exceeded his credit line.
McAllister said Tuesday he filed for bankruptcy to protect his inventory and is searching for an investor.
The 2001 first-round draft pick was released by the Saints in a salary cap move last month and is now looking for a new team. He was due $7 million next season.
McAllister also owns a luxury vehicle dealership in Jackson.