The Italian was fired in February having led Leicester to a shock top-flight triumph in 2015-16 and had been out of work until being confirmed as Nantes' coach this month.
Ranieri led Monaco to promotion to Ligue 1 in his previous spell in French football and the 65-year-old is now hoping to put his time at Leicester behind him.
"It was a fantastic experience," Ranieri told reporters at his presentation on Monday. "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."
Nantes finished seventh in Ligue 1 last season after winning three of their last five matches under Sergio Conceicao, who has moved on to Porto, and a keen Ranieri believes he can build on the work done by his predecessor.
"I've watched a lot of the matches, I'm not going to say the names but there is quality, I saw when the team won but also when it lost," Ranieri added. "But I want to see the players who are suffering for the club.
"Union is very important for me and every coach plays the football he knows. Conceicao had a very compact organisation with very fast counter-attacks. My philosophy is not really different. He played in Italy, I'm Italian - it's the same."
Ranieri continued: "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.
"I'm not going to say that we're going to win this or that, we have to work a lot to achieve good things. France is a nation of wine. You have to work every day, but there are years when it is very good and others where it is not good. I hope the fans will be behind us."