The 25-year-old defender is a former Italy under-19 international and has agreed an 18 month deal with the club.
Lanzoni recently left Oldham after turning down a new contract with the Greater Manchester club. In his spell with the Latics Matteo made 15 appearances, scoring two goals.
Manager Gary Johnson is delighted to add Lanzoni to the Glovers squad: “I have seen him a few times when I have watched Oldham this season, and I was impressed by him.
“He is a typical Italian defender who can play anywhere across the back four, and he’s introduced himself to the lads this morning in training by knocking a few about; he’s competitive.
“In January it’s hard to sign players as opposed to loans, but we are delighted to have signed Matteo on a permanent deal.”
On his move to Huish Park, Matteo said: “I am delighted to sign for Yeovil Town. It is a great opportunity for me to play Championship football and I am looking forward to the challenge ahead.”