"I have been talking with (new Italy coach Antonio) Conte who asked me if I was ready to play again for the Azzurri and I told him that I was," the Juventus star told Gazzetta TV.
"It was a difficult decision to take. I had wanted to stop playing for the national side but he (Conte) took over and he asked me to lend a hand.
"I am happy to do that and we are hopeful we can achieve great things together."
Conte coached Pirlo at Juventus for the last three seasons, in which they won the Serie A title every year, before taking over from Cesare Prandelli as national coach after Italy failed to get past the group stages at the World Cup.
Pirlo is currently sidelined until October with a hip injury, which means he will miss Italy's Euro 2016 qualifier against Norway in Oslo on Tuesday.
Conte was in charge of the Italy side for the first time on Thursday when his side defeated World Cup semi-finalists the Netherlands 2-0 in Bari.