Philadelphia's Shyne Jewelers said in the lawsuit the 25-year-old knowingly provided a counterfeit check for the merchandise he ordered.
"Davis knew that the cashier's check was counterfeit and he acted intentionally and with malicious intent," the suit says.
The lawsuit asks Davis to either return the jewelry or pay the $250,000 plus interest in addition to damages.
Among the unpaid jewelry, Davis reportedly bought a $130,000 green Richard Mille watch, a $30,000 Rolex and about $72,000 worth of pendants. He also had another Richard Mille watch repaired for $19,000.
The Baltimore native has gained notoriety thanks to his work in the ring, totaling a 23-0 career record with all but one bout decided by knockout. He won the WBA lightweight title in December with a knockout win over Yuriorkis Gamboa.
ESPN's Dan Rafael rated Davis the No. 5 overall fighter in the division, which is up to 135 pounds.
While he recently said he plans to have a net worth of $60 million in 2020, this lawsuit could cut into his total.