The 65-year-old, who is highly respected in the game, won his first top-flight title with Leicester in 2016 before seeing his time at the club cut short following their struggles to defend their title.
Ranieri has coached the likes of Napoli, Fiorentina, Valencia, Atletico Madrid, Chelsea, Juventus, Roma, Internazionale, Monaco as well as Greece but while he has secured promotion with a number of sides, his only other silverware was in the form of cup competitions.
And after being unveiled to the Nantes supporters on Monday, Ranieri says he is determined to forget what happened at Leicester as he embarks on a new challenge.
He said: “It was a fantastic experience. The love that the people of Leicester gave me at my departure was even more incredible than at the time of the title.
“Now I want to forget Leicester. It was something unique. But I arrive at a club that has won eight titles in France, a historic club with very beautiful facilities, so I am honoured.
“I am very happy to be here. I have already come here with Monaco. I remember the club in Ligue 2, the fans were fantastic.”
He added: “My motivation is always strong, that’s why I continue to be a coach. I have to prove every day to myself.
“I’ve made a career, but I still have to prove myself to Nantes. My passion and my love for football, for the players, to work well, are very strong.
“I am very nervous when I am at home with my wife, I prefer to be here. My wife says I will be happy. I am, I missed it a lot.