The Greece international had been close to joining Premier League outfit Arsenal but he will instead replace Mehdi Benatia at the Stadio OlimpicoRoma have confirmed the signing of Olympiakos defender Kostas Manolas for an initial fee of €13 million.
The 23-year-old defender had been on the verge of joining Arsenal but the Gunners' €10m bid was rejected, thus allowing the Giallorossi to pounce.
"Konstantinos Manolas is now a Roma player," read a Tweet posted on the Serie A side's official Twitter profile on Tuesday evening.
Roma were in need of a replacement for the Bayern Munich-bound Mehdi Benatia and they agreed a fee with Olympiakos - which could could rise to €15m depending on bonuses - just hours after the Moroccan completed his move to the Allianz Arena.
The Greece international, who could make his debut in Saturday's Serie A opener against Fiorentina at the Stadio Olimpico, has penned a five-year contract with Rudi Garcia's side.