The River Plate number one, understudy to Roberto Abbondanzieri for the Copa America finalists, has joined the Rome outfit on a five-year contract.
"I wanted Lazio and Lazio wanted me," Carrizo, 23, told La Gazzetta dello Sport. "They showed this by carrying out a lengthy and difficult negotiation.
"Now I hope to repay the confidence they showed in me."
The transfer may come as a surprise to Lazio fans accustomed to the tight ship run by club president Claudio Lotito, who is careful with finances after the previous free-spending reign of Sergio Cragnotti - which led the Biancocelesti deep into debt.
Peruzzi retired at the end of last season, leaving coach Delio Rossi keen to bring in a quality shot-stopper as his team ready themselves for the Champions League qualifiers.
Carrizo is understood to be preparing to apply for Spanish citizenship.