Ranieri confident of keeping Parma up
The 55-year-old former Chelsea and Valencia coach replaces Stefano Pioli, who was sacked following Sunday's 3-0 league defeat at Roma which left Parma second from bottom.
"I believe we can stay up and I took the job on because I believe in this project," Ranieri said. "I've seen Parma play this season. They have been playing well, but I want them to be more cynical. I'll be happy to swap good football for better results."
Ranieri returns to coach in his native Italy after an absence of nearly 10 years.
After spells at Cagliari, Napoli and Fiorentina, he left Italy in 1997 to coach in Spain and spent two years at Valencia and one at Atletico Madrid.
He then moved to England to take charge of Chelsea where he spent four years and took the London club to the semifinals of the Champions League in the 2003-04 season.
Ranieri was sacked by Chelsea's Russian billionaire owner Roman Abramovich in May 2004 and was replaced by Jose Mourinho.
A month later Ranieri rejoined Valencia for a second stint, but was sacked the following February after the club were knocked out of the UEFA Cup.
He then returned to Italy to work as a television pundit.
Pioli became the seventh Serie A coach to be fired this season.