Gervinho, 24, joins the club on a "long-term contract" after helping Lille to secure the Double last season when scoring 18 times in 49 games.
The Ivory Coast international's transfer had been held up due to paperwork issues but he has now officially become the first high-profile signing of the summer for the Gunners.
“Gervinho is a player that can play in a number of positions up front. He can play on the right, on the left and through the middle," Wenger told the club's official website.
"He has qualities that I find very important, like his movement off the ball. He has the qualities we like technically.
"He is good one against one, he is strong and was the best provider in the French league with assists and he scored 15 goals. I think he is a very good addition to the squad.”
Gervinho said: “It’s a great feeling to be an Arsenal player. I’m very happy. I’ve always dreamed to play for this club. I’ve achieved this dream now and I am so happy. It’s one of the most beautiful days of my life.
“I’m very happy to have the chance to work with Arsene Wenger. I came here because I believe that he can improve my game and help me reach another level, but the most important thing for me is that I bring a lot to the team for whom I’m playing.”
Meanwhile, the club have confirmed that midfielder Denilson will be returning to former club Sao Paulo on loan.
Denilson said: “I will be playing in Brazil next season as I felt that this is a good opportunity for me to play regular first-team football.
"I move away with sadness because I have so many friends at Arsenal and everyone has always been so supportive towards me.
"I want to say thank you to the club, and of course, also a big thank you to all the Arsenal fans who are very special.
"I'm now focused on doing well in Brazil next season, but will always be looking out for the Arsenal results. It is a great club with many great players, a good team spirit and a top-class manager. I wish you well for next season."