Wednesday's move, which appears designed to help the Orioles trade Villar out of Baltimore ahead of Monday's non-tender deadline, was first reported by MASN Sports.
The Baltimore-based sports network reported Villar was placed on outright waivers after the Orioles were unable to find a suitable trade partner for him before the deadline.
The 28-year-old turned in a career year for Baltimore last season, hitting .274 with career highs in hits (176), home runs (25) and RBIs (73). He ranked third in stolen bases in the American League with 40.
A switch-hitter who led the Orioles in runs (111) and triples (5) last season, Villar is due a big raise in salary arbitration, and MASN reports that the rebuilding Orioles would rather not spend huge money on him.