Harris pleaded guilty to a misdemeanor possession charge. He also was sentenced to 80 hours of community service, two years probation and agreed to complete an NFL drug program.
Harris originally faced a felony possession charge after the Missouri Highway Patrol found more than 35 ounces of marijuana in his car last March.
According to TMZ, Harris will not get credit for time served.
He also faces punishment from the NFL.
Harris, 26, made 18 catches for 224 yards and a touchdown in the regular season.