Dykstra, who hit .285 for the New York Mets and Philadelphia Phillies from 1985 to 1996, was sentenced after a judge refused to let him pull back his no-contest plea to grand theft auto and filing a false financial statement, KTLA-TV, Los Angeles, reported.
Prosecutors said Dykstra, 49, and two co-defendants tried to lease luxury cars from area dealerships by providing fraudulent credit information.
Co-defendant Robert Hymers, Dykstra's 27-year-old accountant, pleaded no contest to one felony count of identity theft. The third defendant, Christopher Gavanis, pleaded no contest to one felony count of filing a false financial statement.
While the Web site baseball-reference.com said he earned $36.5 million as a player, court records show that by July 2009, he was in bankruptcy owing $21 million in loans.