Properzi wore the Italian national jersey 54 times during his long playing career and was a constant in the Azzurri scrum. He played in three World Cups and won the Italian Championship seven times, the last with Benetton in 2002/03.
Properzi has plenty of Heineken Cup experience and earned 16 caps with Treviso.
Leaving Treviso is former Captain Franco Smith, who is going home to South Africa, after three years with the North Italian side. Since joining the Italian club Smith has played for Treviso in the Heineken Cup and the Super 10 as well as assisting with the technical preparation of the team.
Smith will leave for South Africa in mid August after competing in a number of pre-season friendlies.
Benetton will be hoping to build on last season's three Pool victories when they start their campaign against Ulster in Belfast on Friday, 21st October.