The Catalan giants confirmed on Monday that they had agreed to sign the midfielder on a free transfer following his release from AC Milan.
Kessie was officially presented as a Barcelona player on Wednesday, competing a medical at the club's training ground before signing on a deal until June 2026.
The Ivory Coast international said that not too many players in world football would be able to turn down the La Liga giants, and he is looking forward to meeting his new teammates in the coming days.
"There aren't many players who could say no to Barca, it's the greatest club in the world. I am really looking forward to starting training and meeting all my new teammates," Kessie said at his unveiling. "I am ready to do what the coach needs. I consider myself a midfielder, but I'll play in whatever position he wants."
Kessie was an important player for Milan during the 2021-22 campaign, scoring seven goals and registering one assist in 39 appearances in all competitions.
Meanwhile, he has left the Italian outfit with a record of 37 goals and 16 assists in 223 appearances since making the move from Atalanta BC.
A number of clubs had been linked with the midfielder when it became clear that he would be leaving San Siro, but Barcelona were able to convince him to make the move to Camp Nou.
Barcelona president Joan Laporta also spoke on Wednesday at the unveiling of Kessie, branding the Ivory Coast international "a great professional".
"Welcome, Kessie," Laporta said at the presentation. "I'm very happy to sign this player. He's a great professional and he has always wanted to come to Barcelona. I also want to thank his representative and his family. The coach wanted him to strengthen the team."
Kessie has arrived to boost a midfield that includes the likes of Pedri, Gavi and Sergio Busquets, but there remains uncertainty surrounding the future of Frenkie de Jong.
Manchester United had seemingly been on the verge of signing the Netherlands international last week, but Laporta has since said on more than one occasion that the midfielder is not for sale.
"Frenkie is not for sale. He is a Barcelona player. We don't want to transfer him," said the club president when asked for an update on the situation on Wednesday.
Meanwhile, at the start of this month, Laporta told reporters: "There are clubs that want him, not just United. We have no intention of selling him, he wants to stay. Frenkie is considered as one of the best midfielders in the world by all the experts. We are happy to have him.
"I'm going to do everything I can in my power so that Frenkie stays here, but there's also a salary issue and that would have to be adjusted."
Andreas Christensen has also been confirmed as a Barcelona arrival this summer, with the Denmark international joining the club following the expiration of his contract at Chelsea.