The Croatia international has joined the west London club on a season-long loan as part of the same deal which saw Thibaut Courtois head to Real Madrid last week.
Kovacic will now be hoping to impress new manager Maurizio Sarri as he bids to try and work his way into the first team at Stamford Bridge this season.
The 24-year-old earned plenty of praise for his strong performances for Croatia as he helped his country to reach the World Cup final in Russia this summer.
He will now be hoping to swiftly adapt to the rigours of English football as he bids to try and help Chelsea FC enjoy a strong campaign under Sarri.
And Chelsea FC director Granovskaia feels that Kovacic will be the perfect addition for the west London club.
Speaking in an interview with Chelsea FC’s website, Granovskaia said: “We are very happy to welcome Mateo to the Chelsea family.
“He is a perfect fit for us this season, his style is well suited to how Maurizio wants to play and we are sure he will prove to be a valuable asset for the club.”
Chelsea FC will be aiming to at least break back into the top four next season after they finished in fifth place in the table last term.
The west London side did manage to end last season on a high by beating Manchester United in the FA Cup final.
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