The 31-year-old becomes the Blues’ second foray into the Premier League summer transfer window, following the signing of English forward Raheem Sterling from Manchester City.
The Senegalese international, who made 312 appearances for the Naples outfit, will reportedly earn a weekly salary in the region of £160,000 plus bonuses, per Sky Sports.
“I’m very happy to be here with this team at Chelsea,” Kalidou Koulibaly said via the Blues’ official website.
“It’s a big team in the world and my dream was always to play in the Premier League. Chelsea came first to get me in 2016 but we didn’t make it.
“Now when they came to me I accepted it because they really wanted me to come to the Premier League to play for them. When I spoke to my good friends Edou and Jorginho they made my choice easier so I’m really happy to be with you today.
“I want to thank the fans because I saw a lot of them in London and on the plane everybody was happy for me to be here. So I want to thank them and I hope the season will be really good and we will give some good moments to the fans.”
Koulibaly had 12 months left on his contract with Napoli and was a subject of transfer interest from Turin giants Juventus, who are keen on a potential replacement for Matthijs de Ligt.
Chelsea are not only getting one of Europe’s elite and most experienced defenders in the former Napoli man but a true leader who captained the Senegalese national team to their maiden Africa Cup of Nations title earlier this year.
The 31-year-old fits the bill at Stamford Bridge and will slot right into the defence line following the departure of the centre-back duo of Antonio Rudiger and Andreas Christensen.
Speaking on Koulibaly, Chelsea manager Thomas Tuchel added: “I’m very happy with him signing and joining our team.
“He’s now the second signing of the summer and again we have a strong player, a strong personality with big experience. From our point of view, he’s a perfect addition to the group.”
The Senegalese international has joined the Chelsea squad in Las Vegas as they prepare for their pre-season opener against Mexican outfit Club America on Sunday.
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