The former Valencia, Chelsea and Roma boss succeeds Gian Piero Gasperini, who was sacked on Wednesday after just three matches of the new Serie A season
Ranieri will now take charge of Inter’s training on Thursday before being officially unveiled at a press conference on Friday ahead of his first game on Saturday at Bologna.
A statement from the club on Thursday read: “Claudio Ranieri is officially the new coach of Inter.
“Ranieri has signed a contract with Inter until June 30, 2013.
“All of Inter has the pleasure of welcoming Claudio Ranieri and his staff.
“Ranieri will guide today’s training session and will be unveiled tomorrow to the press.”
Inter sacked Gasperini after a shocking 3-1 defeat at newly-promoted Novara – the team’s fourth loss in five games this season.
Ranieri, 59, becomes Inter’s fifth coach in the past 15 months following Gasperini, Leonardo, Rafa Benitez and Jose Mourinho, who had won the Treble before moving to Real Madrid.
Having been out of work since leaving Roma in February, Ranieri has previously admitted he is looking forward to the challenge at Inter.
He said ahead of his appointment: “Inter are a great team. They have had a bad start to the season and I will have to talk to the team to understand why that was.
“I will have to bring enthusiasm and a change of gear in order to wake up the team.
“I cannot promise that we will win this or that but I believe this team has a lot to give and we must prove it.”