Arsenal have sold Gabriel to Valencia for a fee understood to be £10m.
The Brazilian defender had fallen down the pecking order under Arsene Wenger after signing from Villarreal in January 2015, following the arrivals of Rob Holding and Shkodran Mustafi.
Gabriel made 64 appearances for the Gunners during his two and a half years at the club, soring once and winning the FA Cup on two occasions.
The 26-year-old made just 19 Premier League appearances in his final campaign at the Emirates Stadium.
Valencia announced the signing in a statement on their official website.
“Valencia have reached an agreement with Arsenal for the transfer of … Gabriel Paulista.
“The Brazilian player has signed for the next five seasons until June 30, 2022, with a termination clause of 80 million euros.”
Gabriel sustained a serious knee injury in Arsenal’s final Premier League game of last season and did not feature in pre-season.
Gabriel could be the first of a number of departures at the Emirates, with Lucas Perez, Calum Chambers and Joel Campbell also linked with moves away.
Meanwhile, Arsenal have turned down an approach by Inter Milan to sign Mustafi on loan