He becomes the Gunners’ second new recruit of the summer transfer window after Spain goalkeeper David Raya signed on a permanent basis from Brentford on the back of an initial loan spell.
Comfortable operating at both centre-back and left-back, Calafiori joined Bologna in August 2023 and went on to make 33 appearances for the Serie A outfit in all competitions.
The versatile full-back rose through Roma’s academy ranks as a teen and made his debut for his boyhood side in 2020 before spending a year in Switzerland with Basel.
In his one and only season back in Italy, Calafiori played a key role to help Bologna secure Champions League football for the first time in the club’s long history.
Arsenal sporting director Edu said: ‘It has been a great team effort in completing this transfer and we welcome Riccardo to the family.
‘We identified Riccardo as part of our strategy to sign players who fit our profile and will reinforce our squad to compete at the highest level. He is 22 but brings quality and experience. He will quickly grow into being an Arsenal player.
‘Riccardo has consistently shown his quality for his club and country. He was one of the best players in Serie A last season, and gave strong performances for Italy in the Euros this summer.
‘Mikel and our coaches are excited to start working with Riccardo, and we all look forward to seeing him in our shirt.’
Gunners boss Mikel Arteta added: ‘We welcome Riccardo and his family to Arsenal. He is a great signing and gives us huge strength to reinforce our defence.
‘Riccardo is a big personality and character, with specific skills which will make us stronger as we push to win major trophies.
‘He has already shown great development in recent seasons with his performances for both Bologna and Italy, with his progression and development in the past year being really impressive.
‘We’re looking forward to working with Riccardo, integrating him into the squad, and supporting him in the years to come.’