Former Sassuolo coach Eusebio Di Francesco signed a two-season deal at Roma on Tuesday after the clubs agreed a compensation package.
Roma have been looking for a new coach since Luciano Spalletti left last week to join fellow Serie A outfit Inter Milan.
"We wanted someone who could come in and get the very best out of our first team players and also help bring through some of the great young talent coming out of our academy," said Roma president James Pallotta.
"Our new sporting director Monchi singled out Eusebio Di Francesco and, with his style of play, we believe he's the right fit for Roma."
The 47-year-old, who played for Roma for four years and was part of the 2001 title-winning side, was photographed with a broad smile in front of a group photo of that year's team as he was unveiled.
"I am extremely happy to be able to return to Roma, to coach a club that has always meant a lot to me," Di Francesco said.
"I will give everything I have to make sure this team gets the results it deserves."
He has been a long-time target for the capital club, despite having extended his Sassuolo contract to 2019 just last year.
Di Francesco joined Sassuolo in 2012 and steered them to the 2013 Serie B title.
Although he was sacked in January 2014 following a run of poor results, Di Francesco was brought back just two months later and has since kept Sassuolo in Serie A.
Roma finished runners-up last season and will play in the Champions League next term.
Earlier on Tuesday, Roma announced that Mexican defender Hector Moreno had become their first signing of the close-season from PSV Eindhoven.