Officials say it was located Wednesday morning, and was discovered in the Los Angeles River off Downey Road in Vernon. Meanwhile, the search continues for the person or group who stole the vehicle from the National Guard Armory last week.
The Humvee, which the FBI said is worth about $120,000, was "up-armored," meaning it had been upgraded and is considered a combat vehicle.
A reward of up to $10,000 had been offered for information leading to the vehicle, but it's unclear if law enforcement or a civilian found it.
The FBI thanked the California Army National Guard, California Highway Patrol and Los Angeles police for helping its Major Theft Task Force recover the Humvee.
Anyone with information about the person or group responsible for the theft is urged to call the FBI's Los Angeles Field Office at (310) 477-6565.
The FBI says a theft from a military facility carries a statutory maximum sentence of 10 years in federal prison.
RELATED: FBI searching for armored military Humvee stolen from National Guard facility in Bell
FBI searching for armored military Humvee stolen from National Guard facility in Bell
The Associated Press contributed to this report.