Casty, 26, has played 88 Super League matches for the Dragons since their inaugural year in 2006.
New coach Trent Robinson said: “I am very proud to see Rémi signing for the club until 2014. He is a player who is completely committed to the club and who represents the future of the Dragons. He has progressed greatly since his arrival and has just proven his fidelity to the Catalan club. He is one of the players who will be called on to build the next generation of the team. He is still young but he has the attributes to become the future leader of the Dragons’ pack.”
CEO Christophe Jouffret added: “Rémi had two years remaining of his old contract with us, up until the end of 2012, but it is important for us to retain the services of this front-row forward who, having made progress last season, is sure to become the masterpiece of our pack. Off field, Rémi is an exemplary man, proud of our club and his sport. This pure product of Ornaisons rugby school is also a symbol of the development work carried out by Lézignan over many years.”