The Barbarians will take on Argentina at Twickenham on 1st December in the annual Killik Cup match.
The announcement follows the Baa-Baas stunning nine-try victory over England at the weekend.
Speaking about the new fixture, Barbarians President Micky Steele-Bodger said:
"We're delighted to take on the Pumas once more and with all the talent at our disposal it should be another match full of exciting attacking play.
"Twickenham will provide a great stage and we'll be doing our best to really test Argentina as they continue their build-up to the 2019 Rugby World Cup."
The two teams last met in the 125th Barbarians anniversary match in 2015. Argentina won that contest 49-31 in a match that saw a total of 12 tries scored.
Tickets for the 2018 Killik Cup match go on general sale at 9am on Thursday 31st May at Ticketmaster, priced from £20 (Adult) and £15 (Junior) plus booking fees.