Scolari, who led Brazil to their fifth and last world title in 2002, was officially presented as coach of the 2014 World Cup hosts, while Carlos Alberto Parreira, in charge when they won their fourth World Cup in 1994, was named technical director.
"We have the obligation to win the title; we are not favourites at the moment but we intend to become favourites during the competition," said the man known as Felipao (Big Phil). "Third or fourth place is no good for a country that has won five World Cups."
Scolari, who has inherited a young side who are seen as lagging behind teams such as Spain, Argentina and Germany, will have to cope with huge expectations from his 190 million compatriots.
Scolari replaced Mano Menezes who was surprisingly sacked last Friday, just as his team appeared to be taking shape.
The unveiling comes two days before the draw for the next year's Confederations Cup, also to be hosted in Brazil, in Sao Paulo. Scolari's first game in charge is scheduled to be a friendly away to England in February.
Brazil's vast and fickle army of supporters always expect them to win the World Cup and the pressure will be even greater as the country hosts the event.
Their failure to win on home soil in 1950 still rankles and the members of that team were never wholly forgiven for losing the decisive match to Uruguay.
Scolari said it was water off a duck's back. "If you don't like pressure, it's better to go and work in the Bank of Brazil, or outside on the corner or sit in an office and do nothing," he said.
"It would not be right if there was no pressure and the players thought the target was just to play at the World Cup.
"This would be one of our most important titles - the sixth title, at home at our second opportunity."
Scolari said he felt under much greater pressure when he took over for the first time in 2001 when Brazil were in danger of missing out on the following year's World Cup.
"It would have been the first time that Brazil would have missed a World Cup, that was when I felt under pressure," he said.
Scolari, 64, and Parreira, 69, both said they felt rejuvenated by the challenge.
"I feel like a young boy, starting all over again," said Parreira, who also coached Brazil at the 2006 World Cup when they reached the quarter-finals.
"The Brazil team does you good, all that adrenalin. It's a marvellous challenge, to come back to the team for a World Cup here in Brazil, you can't describe it."
Both pointed to their past experience in Brazil and abroad.
Scolari has led Portugal at three major tournaments and coached in England, Uzbekistan, Kuwait and Saudi Arabia, while Parreira has coached the national sides of Kuwait, United Arab Emirates and Saudi Arabia at the World Cup.
Scolari was proud of his record with Portugal who had a reputation for underachieving before he took over.
"We revolutionised the relationship with the supporters," said Scolari. "I maybe didn't win anything but the work we did was worth more than 10 or 20 titles."
Former Barcelona coach Pep Guardiola had been suggested as a possible replacement for Menezes but Brazilian Football Confederation (CBF) president Jose Maria Marin said there was ample domestic talent.
"We have won all of our titles with Brazilian coaches who have taken their knowledge beyond these frontiers," he said. "Our country has a great number of competent coaches who deserve to hold this position."