Former Chelsea manager Maurizio Sarri says joining Serie A champions Juventus is the "crowning moment" of his 29-year coaching career.
The Italian, 60, joined Chelsea from Napoli in 2018, but left the club last week to return to Italy after just one season in charge.
Speaking at his first news conference, Sarri said he wanted to help Cristiano Ronaldo continue to break records.
He also addressed criticism from Napoli fans that he was a "traitor".
Juventus sporting director Fabio Paratici said Sarri "has always been the first choice" for the job.
"I gave everything to Napoli," said Sarri, speaking at the Allianz Stadium in Turin, dressed in a club suit and tie.
"Then I had a doubt and my feeling was my journey there was over. I received proposals from other clubs and decided to go abroad and not pass from one Italian club to another.
"I had a wonderful experience in the Premier League but then I felt a professional and personal need to come back to Italy.
"Juventus are the best Italian club at the moment; they offered me the opportunity to return to Italy. It is the crowning achievement of a long career, that for 80% of it was extremely tough."
Sarri led Chelsea to third in the Premier League and won the Europa League - the first trophy of his career.
But throughout his time at Stamford Bridge there was repeated speculation about his position, with Chelsea fans expressing their discontent at tactics and team selections.
"I arrive with scepticism, just as I did with all my other clubs," he added. "I understand that, but I know only one way to change that and that is to win and convince while entertaining and getting results."
Sarri succeeds Massimiliano Allegri, who won the league title in each of his five seasons at Juventus since taking charge in 2014.
But Italian Allegri failed to win the Champions League and reached the quarter-finals last season despite signing Ronaldo last summer for £99.2m.
"Juventus will go there to win (the Champions League), but we are aware there are eight or nine other teams who are in the same situation," said Sarri.
Sarri managed Napoli for three seasons from 2015 to 2018 and has been criticised for moving to their rivals.
"(At Napoli) my first thought was to defeat Juventus, my moral duty was to defeat them. I gave 110%. We didn't succeed but that was a sporting rivalry and my professionalism will be to give my best for this club.
"What I did in the past was sometimes achieved with the wrong words and methods, but they could be appreciated from an intellectual point of view."
Sarri said working with five-time Ballon d'Or winner Ronaldo, the club's top scorer last season with 27 goals, would be "moving on to the next level".
"This is a player with every record in world football and I'd like to help him set another," he said.
He was also asked if he would wear a suit or his favoured tracksuit on the sidelines.
"I would prefer not to wear the suit and tie on the pitch. The important thing at my age is that they don't send me out there naked," he joked.