Inter Milan have confirmed Leonardo as Rafael Benitez's replacement, giving the Brazilian a one-and-a-half-year contract as their new manager.
Speculation had linked the former AC Milan coach with the position even before Benitez officially parted company with the European champions, and the Nerazzurri have now officially confirmed his appointment.
The 41-year-old, who had one season in charge of Milan during the 2009-10 campaign, will officially start work with the Serie A champions on Wednesday.
A statement on the club's official website read: "Welcome to Leonardo. It will be the Brazilian coach to lead the team from December 29.
"Leonardo has a contract that will bind him to Inter until 30 June 2012. For Leonardo, the most sincere and good luck, we believe that he has the class and experience of a champion and his mentality will get the team together to get results."
Club president Massimo Moratti had insisted earlier that he would not be naming Benitez's successor until after Christmas, but has now reneged on that to appoint the former World Cup winner.
The appointment would be unlikely to go down well with Milan supporters - the vice-president, Adriano Galliani, spoke on Thursday of Leonardo's "important history with Milan" - but Moratti does not believe it would constitute a snub.
"I never make this kind of reasoning," he said. "I do not live out of spite, and I would be disappointed if it were interpreted in this way."
Inter veteran Javier Zanetti has given his support to Leonardo.
"I know Leonardo well," he said. "He is a very intelligent person, someone who is always on the ball. He has a lot to give as a coach thanks to the experiences he gathered as a player and as a man."
Leonardo takes over a side that are in seventh place in Serie A, 13 points behind leaders Milan. Apart from attempting to bridge that gap, one of his primary tasks will be attempting to retain the Champions League when the competition resumes in February.
Inter must overcome Bayern Munich over two legs if they are to stand a chance of keeping the trophy they won when Jose Mourinho's side beat the Germans in May. Benitez's six-month stay at the San Siro was officially ended yesterday. Despite lifting the Italian Super Cup and the FIFA Club World Cup during that time, the Spaniard had struggled to adapt to life as the popular Mourinho's successor, and seemed to issue Moratti with an ultimatum over transfer funds earlier this week.
That led to the breakdown of his relationship with Moratti, who, after Benitez left the club, was quoted as saying: "I'm sorry the relationship with Benitez is over, but the split had now become inevitable."