Sanchez moved to the Premier League last August and has enjoyed a superb debut campaign in England, scoring 22 goals in all competitions.
"When I arrived at the club I didn't know the players that well, but I was really surprised by everyone's quality," the 26-year-old told the club's official website.
"I am not saying this just because it's my obligation to do it. Every Arsenal footballer has amazing quality. Being part of a team like this makes me very proud. I am willing to win many titles here.
"Santi Cazorla is a spectacular player. You never know whether he will kick the ball with his right or left foot. Also, he moves with short but quick strides, which is a remarkable trademark too.
"Although I knew about his quality, playing alongside him makes me very happy."
