Maresca has signed a three-year contract at the King Power Stadium and has been tasked with masterminding an immediate return to the Premier League.
Leicester suffered relegation to the Championship in the just ended season after finishing 18th on the league table.
Maresca helped Manchester City win an unprecedented treble last season as part of Guardiola's coaching staff.
Maresca had spells as a player at Juventus, Sevilla, Olympiacos, Malaga and West Bromwich Albion.
The 43-year-old has also held a coaching role at West Ham United when Manuel Pellegrini was in charge at the London Stadium.
Maresca only job as a full-time boss lasted 14 games as manager of Serie B side Parma in 2021.
He will come in as a replacement for Dean Smith, who failed to preserve Leicester's top flight status after taking over from Brendan Rodgers in April.
Maresca told Leicester’s official website: “I’m very excited because of the club (I’m joining) and because we have a big season ahead of us.
“At the beginning, the target is to play in the best way we can. From there, we can build, day by day, our idea and our philosophy, and the most important thing is to try to win games.
“First of all, we’re going to give 100 per cent, absolutely, because the club deserves this. It’s our job, our duty to do that. Then, as I said, day by day, step by step, absolutely we’re going to improve.”
Leicester chairman Aiyawatt Srivaddhanaprabha said: “Enzo brings a combination of personality, method and ambition that meets extremely well with the footballing direction we are looking to take.
“His philosophy has been built over a rich and varied career, including an outstanding education as a coach, and fits with the vision we have for this next chapter in Leicester City’s history.
“Enzo’s profile has stood out to us for some time – a feeling that was only enhanced upon meeting him and listening to his enthusiasm for the challenge ahead. I have no doubt he will be warmly welcomed by our supporters and that together we can reset the club’s course towards future success.”
