The talented 28-year-old – nicknamed Speedy because of his middle name – will move to the BT Sport Cardiff Arms Park after starring for Argentina against New Zealand, South Africa and Australia in the Rugby Championship.
The 37-cap back played in four games at the 2011 Rugby World Cup, scoring tries against Romania and Scotland. He underlined his attacking talents by making the second most line breaks (22) throughout the tournament.
Amorosino first made his mark on the Argentine Sevens circuit before joining Leicester Tigers in 2009, scoring four tries in his first six matches. He later had playing spells at Top 14 clubs Montpellier and Oyonnax.
Director of Rugby Mark Hammett said: “We’re really pleased that Lucas will join up with the squad in the coming weeks. He has a lot of international experience and can play on the wing or at full back so certainly strengthens our options.
“Lucas is contracted to us until the end of the season and there is an opportunity to extend that for longer if we feel it is a good fit for both of us. Paul John has looked at him closely and we feel he can be a real success at Blues. I know that Lucas is also determined to take this opportunity and we look forward to his arrival.
Amorosino added: “I’m delighted to be joining a region with such a strong and proud history. Firstly, I would like to thank Mark Hammett and Richard Holland for giving me this opportunity. I will be working hard to repay the faith they have shown in me and give the fans of Cardiff Blues some great performances to enjoy.
“I am looking forward to joining my new team-mates and settling into life in Cardiff. I know the region has a lot of top quality international players and there is great ambition to achieve success together. I hope to play my part and to give the fans the success they deserve.
“I’m excited by the challenge of returning to the United Kingdom to play my rugby and I cannot wait to get started.”