The 27-year-old, who helped Malaga to a fourth-place finish in La Liga last season, had been heavily linked with a move to north London in recent weeks.
And Wenger is thrilled to have finalised the transfer as Cazorla follows Lukas Podolski and Olivier Giroud into The Emirates this summer.
“Santi Cazorla is a great signing for us,” Wenger said. “He is a player with good experience at both club and international level, who will add significant quality to our squad.
“He is a versatile, attacking midfield player who can play comfortably on either side of the pitch or centrally.
“He has good pace, is technically gifted and will be a huge asset to Arsenal football club. We are delighted that he is joining us.”
Cazorla, who also spent two seasons a Villarreal, vowed to help the Gunners end their seven-year wait for a trophy next season.
“I’m so happy to be joining Arsenal,” said Cazorla. “This is a club with great players, a fantastic stadium and huge support.
“The club has one of the best managers in football and their style of play is recognised and admired all over the world.
“I’m so excited to be joining one of the greatest teams in Europe and also in the Premier League. I will do my best to help Arsenal challenge for trophies and make all the supporters happy.”
Former Arsenal captain Cesc Fabregas on Twitter: “I’m so happy to hear that my mate Santi Cazorla is finally a gooner. Top guy, special player. A great signing! Come onnn!”
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