Volpi spent a week with the Swansea based region earlier this year where he trained with the senior squad. And his trial with the region has persuaded head coach Allen Clarke to hand him a permanent contract.
The 23-year-old will become the first Argentinian to represent the Ospreys and is their seventh new signing ahead of the 2018/19 season.
“Guido is a fantastic athlete, with size, pace and the ability to offload,” said Rugby General Manager Dan Griffiths.
“He really impressed during his time with us, not only with his physical capabilities, but also his ability to adapt and learn quickly. Our age grade pathway and academy are bringing through some fantastic talent, but Guido will bring something different.
“We are excited to see how he will progress surrounded by quality players and coaching. There is a real excitement and desire within these young men to be a part of the Ospreys.
“We are looking forward to seeing how the blend of quality internationals and hungry young talent can create a vibrant, competitive environment.”
Part of Argentina’s high-performance programme as a youngster, Volpi played for CUQ Rugby in Buenos Aires before heading to France last summer to sign for Narbonne, captaining the club in the ‘Espoirs’ competition for under-23 teams.
“I am very happy to sign for the Ospreys” said Volpi.
“They are a big club who are ambitious about their goals. It will be my first experience at that level, so I’m really looking forward to it and I hope to benefit from it and grow as a player.”
