Maresca has been Pep Guardiola's assistant at Manchester City since Mikel Arteta's departure to Arsenal, helping the Cityzens to their historic treble this past campaign.
He replaces interim boss Dean Smith, who oversaw just two wins from eight games as Leicester were surprisingly relegated from the Premier League.
Maresca previously worked as City's under-23s boss prior to his stint as an assistant under Guardiola.
His only previous senior managerial role was a tumultuous 180-day spell as Parma boss in 2021, overseeing just four wins from 13 games after they were relegated from Serie A. He returned to Guardiola's coaching staff shortly after.
The Italian has also worked as an assistant manager at Sevilla and West Ham.
Leicester City Chairman Aiyawatt Srivaddhanaprabha said of the appointment: "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."
Speaking on Leicester's website, Maresca said: "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 endured a miserable 2022/23 season, finishing 19th in the league and ending a 10-year spell in England's top flight, which featured their infamous title win and an FA Cup victory.
