Italy have been searching for new leadership since November, when Gian Piero Ventura was dismissed in the aftermath of a disastrous two-legged play-off defeat by Sweden that meant they failed to qualify for the World Cup for the first time since 1958.
For the sake of getting a job at the helm of the "squadra Azzurra of Italy", which was not included on the 2018 world Cup, Mancini refused to continue to cooperate with Zenith in the two years before the end of the contract.
"We'll explain everything about the contract tomorrow, he's very happy and so are we".
Since leaving the Etihad five years ago, the 53-year-old has worked at Galatasaray and Internazionale before heading to Russian Federation to manage Zenit St Petersburg last year.
However, admirers will remember more fondly his 2012 Premier League triumph with Manchester City-at the time their first top-flight title in 44 years-as well as winning three Serie A crowns with Inter between 2006 and 2008.More news: Conte warns Chelsea flops to shape up ahead of Cup final
He began his coaching career with Fiorentina in 2001 and won the Coppa Italia in his first season even though the club was plagued by financial problems.
Mancini, one of the highest-profile foreign coaches to join the Russian Premier League in recent years, signed a three-year contract with Zenit in 2017.
It isn't all bad for the former Sampdoria forward though, who will pick up £1.8 million a year up until 2020 as attempts to take the Italy team through to the next European Championships.
He reached the semi-finals of Euro 1988, and was in the squad that finished third in the 1990 World Cup on home soil.
Under-21 coach Luigi Di Biagio took the reins for March friendlies against Argentina and England.