Jedvaj joins the Bundesliga outfit on an initial two-year loan deal that includes an option for Leverkusen to buy the 18-year-old permanently before the end of the 2015-16 season.
According to a statement on Roma’s official website, they also retain a counter-option on Jedvaj's services. The nature of this was not disclosed.
Leverkusen sporting director Rudi Voller told his club's website: "Tin Jedvaj is a great talent that we have observed for some time.
"We hope that he will take the next step with us.”
Following his arrival in the Italian capital from Dinamo Zagreb, Jedvaj made just two Serie A appearances last term.