"He is a man linked to Juventus and to our story of success," a club statement said, adding he had signed a two-year deal.
The 42-year-old was the standout candidate after Bari coach Antonio Conte, the ex-Juve captain, and AS Roma's Luciano Spalletti announced they would be staying at their clubs.
"He is a young coach, who has gained managerial experience in recent years within the club and has an international outlook thanks to his work with the world champions," the statement added.
This season Barcelona won the Champions League and a Spanish double in 38-year-old Pep Guardiola's first season in charge.
"I think Ferrara can be the Italian equivalent of Guardiola," Italy and Juve defender Nicola Legrottaglie told reporters. "He is ready for this great job."
They made a good start to the season just gone, beating Real Madrid home and away in the Champions League, but an alarming dip in form towards the end of the campaign threatened their place in Europe's top competition and Ranieri was sacked.
"The bitterness remains but it is all part of the game of football," Ranieri told Sky television earlier on Friday in his first public comments since his dismissal.
"I didn't expect it from a club like Juventus."
