Los Angeles County Sheriff's Department deputies found the child Thursday at an encampment along the Los Angeles River, near the 710 and 105 freeways, the agency said.
Deputies said the boy was found with an unidentified man.
In a statement, authorities said they believed the child's name is Anthony. The Sheriff's Department asked for the public's help in identifying the boy or his parents.
On Friday afternoon, an updated news release said the child's mother had been located.
The boy was in the custody of the L.A. County Department of Children and Family Services "and a social worker will be meeting with mother and son to reunite them or to provide the needed services for placement if necessary," the LASD statement said.
"Thank you tothe public, the media, Aero Bureau, and deputy personnel for their tireless efforts in the search for the child's parents," the Sheriff's Department said.