The award follows US Court of Federal Claims' recent decision, which instructed Oshkosh to resume work on its $6.75bn contract to manufacture JLTVs for the US Army.
The army's JLTV programme covers vehicles, installed kits and packaged kits.
Oshkosh JLTVs will replace 55,000 of the US Army and Marine Corps’ high-mobility multi-purpose wheeled vehicles (HMMWVs).
The new vehicles are said to deliver protection, networking and off-road mobility to soldiers and marines during missions.
They are equipped with an EOS R-400S-MK2 remote weapon system, integrated with Orbital ATK's M230 LF 30mm lightweight automatic chain gun.
Oshkosh Defense joint programmes vice-president Dave Diersen said: “This latest order demonstrates that the JLTV continues to be a central piece of the army’s future ground force and a modernisation priority.
“The JLTV programme is moving forward with a focus on giving soldiers and marines the next generation light vehicle they need for their missions.”
The latest order is the third to be placed since the contract was awarded in August 2015.
Oshkosh was selected over Lockheed and AM General to deliver approximately 17,000 armoured trucks and sustainment services under an eight-year contract.
Work under the order will be performed in Wisconsin, and is scheduled for completion in November 2017.
The Oshkosh JLTV will be presented at Modern Day Marine 2016 from 27 to 29 September.
At the event, the vehicle will demonstrate its capabilities, including its medium-calibre weapon system.