The 17-year old starlet has arrived at Emirates Stadium from Southampton for a fee of £12million, that could rise to £15m, and Wenger was overjoyed at the signing.
"We are delighted that Alex has decided to join us. He is an exciting young player who will provide us with creativity and offensive quality," he said.
"Alex is a versatile player who can play in a number of positions. He can play as an attacking centre midfielder, or wide left and right.
"Alex is a perceptive passer of the ball and has a great understanding of the game and looks to be a very good team player.
And the player himself was also over the moon after signing with the North London giants.
"I'm so excited to be joining Arsenal. It's a fantastic club and I'm really looking forward to the opportunity of playing football at the highest level," he said.
"I'm proud to be joining Arsenal, but I would also like to take this opportunity to thank everyone at Southampton for their help and support during the early part of my career, for which I will always be grateful.
"I'm now looking forward to meeting all my new team mates and giving absolutely everything in an Arsenal shirt."