He has represented Argentina at under-19 and under-21 levels and has been selected in the Pumas' squad to play the British and Irish Lions at the Millennium stadium on Monday 23 May. He has six caps for Argentina.
Frank Hadden, Edinburgh Rugby coach, said: "I believe that Francisco will be an outstanding asset to Edinburgh Rugby. He is currently becoming a fixture in the Argentinean national side after captaining their very successful sevens team for the past three seasons. He can play anywhere in the three-quarter line and I'm sure the Edinburgh supporters will enjoy his all-round qualities as a rugby player."
Francisco Leonelli said: "I am looking forward to coming to Scotland and Edinburgh Rugby. It will be a change in environment for me. It will be a great experience in terms of rugby and living in another country."