Clark County District Court Court Judge Jessie Walsh dismissed the case against the 26-year-old singer-songwriter of hits including "Just The Way You Are" and "It Will Rain."
Mars, whose real name is Peter Gene Hernandez, didn't appear in person for the brief hearing in Las Vegas.
He pleaded guilty last Feb. 16 to cocaine possession, but the judge postponed accepting the plea. She gave Mars probation, fined him $2,000 and ordered him to perform 200 hours of community service and eight hours of drug counseling.
Mars acknowledged having 2.6 grams of cocaine when he was arrested in a bathroom in September 2010 after a nightclub performance at the Hard Rock Hotel & Casino in Las Vegas.
His attorneys, Blair Berk and David Chesnoff, said Mars has abided by the requirements. He could have faced up to four years in state prison.
Mars worked with unspecified children's charities and health-related organizations to complete his community service, Berk said Tuesday. She has said the singer appreciated the chance got as a first-time offender to have the felony charge dismissed.
The former child entertainer from Hawaii began his career at age 4 as an Elvis impersonator. He moved to Los Angeles in 2002.
