Former Borussia Dortmund defender Mats Hummels has joined Roma on a free transfer, the Serie A giants have confirmed.

Hummels has been without a club since he was surprisingly released by Dortmund in June, having helped them reach the Champions League final last season.

He led all centre-backs in the competition for line-breaking passes, with 133, but was unable to lead them to victory against Real Madrid at Wembley Stadium, where they were beaten 2-0.

Hummels made a total of 508 appearances across two spells with Dortmund, winning two Bundesliga titles and finishing as a Champions League runner-up on two occasions.

The 2014 World Cup winner was linked with a move to Bologna last month after they sold Riccardo Calafiori to Arsenal, only to fail to agree terms with the Rossoblu.

He has instead joined Danielle De Rossi's Roma, who were in need of defensive reinforcements after allowing Chris Smalling to join Saudi Pro League side Al-Fayha.

Reports suggest he has penned a one-year deal with an option to extend his stay in the Italian capital by a further 12 months, with Roma announcing he will wear the number 15 shirt.

Hummels' debut could come at Genoa on September 15, with his first home outing potentially coming against Udinese one week later.

The Giallorossi failed to secure Champions League qualification last season and will play in the Europa League, with Athletic Bilbao their first opponents on September 26.