Los Angeles Superior Court Judge Barbara Johnson also ordered the 38-year-old woman, who has not been named by most news organizations to protect the identity of her son, to perform 150 hours of community service.
Johnson said the welfare fraud charge would be reduced to a misdemeanor on April 27 if the woman performs the community service and pays the restitution by that date. The woman was expected to move to Georgia later this year and was ordered by the judge to enroll in a community service program there.
In California, pleading no contest plea is the legal equivalent of pleading guilty.
At the trial last year, prosecutors charged Jackson with molesting the teen and conspiring to hold him and his family against their will at his famed Neverland Valley Ranch in central California. The jury acquitted the entertainer of all charges in June of 2005.
The woman took the witness stand during the trial, testifying that for a time she was forbidden to leave the ranch and was intimidated by Jackson's associates.
She refused to testify about the welfare assistance, citing her Fifth Amendment protections against self-incrimination, and jurors said after the trial that her credibility in court factored into their deliberations.
Jackson, 47, has since moved out of the country, and Neverland remains largely shuttered.