Sokratis Papastathopoulos has completed his move to Arsenal from Borussia Dortmund.
The Greek international has joined the Premier League side on a long-term contract for an undisclosed fee.
Before making 186 appearances for Dortmund he played for Werder Bremen, Genoa and AC Milan.
Sokratis makes the switch from Borussia Dortmund where he has won two Bundesliga titles and one German Cup having signed for them in 2013.
He becomes Arsenal manager Unai Emery’s third signing since taking over from Arsene Wenger in May.
The Gunners have already signed defender Stephan Lichtsteiner on a free transfer from Italian champions Juventus, while Germany goalkeeper Bernd Leno has agreed to join from Bayer Leverkusen.
“I feel very good, it is my first day here, everything is special, it is a beautiful moment. I am very happy,” Sokratis told the club website.
“Arsenal is one of the three biggest clubs in the Premier League, it has a lot of fans, a very big history and I am very happy and for the next year I will be here to help the team.”
The 30-year-old defender will wear the number 5 shirt at the club and also has vast experience on the international stage having made 79 appearances for Greece.
Papastathopoulos will link up again with former Dortmund team-mates Pierre-Emerick Aubameyang and Henrikh Mkhitaryan.