The club's official website confirmed the news, saying the midfielder will travel to Sweden for the procedure.
As noted on the Arsenal website:
The club’s medical team and specialists have decided that surgery is required to the plantaris tendon in the Spain international's right foot.
The problem has not progressed during a rehabilitation programme following the injury during the home match with Ludogorets on October 19.
We expect Santi’s full recovery to take approximately three months.
Cazorla was a big loss for the Gunners last season after a knee injury restricted him to just 21 appearances in all competitions, which also saw him miss out on a place in Vicente del Bosque's Spain squad for Euro 2016.
The Spaniard is among Arsenal's most creative players—arguably second only to Mesut Ozil—and his exceptional technique and cultured passing are almost unmatched.
He also carries a goal threat from midfield, having netted 27 goals for the club in his first three seasons—he failed to find the net last year, but he played relatively few games.
Last season aside, the experienced player has largely remained injury-free during his Arsenal career, but fitness problems could become an increasing worry as he gets older, as they were for Mikel Arteta during his time at the Emirates Stadium.
Ozil was able to compensate for Cazorla's loss last year by creating a ludicrous number of chances—144 to be exact, according to Squawka—but having the Spaniard fit is important for the team not to rely on the German too much.