The former Southampton starlet completed his move yesterday.
"It feels fantastic," he told arsenal.com. "I'm delighted to be here and I'm looking forward to pushing on and working as hard as I can for the Club this season.
"I've come to Emirates Stadium a few times this season to watch a few games and I was just blown away by the atmosphere, the fans and everything about it. It would be hard to refuse an opportunity like this.
"To have the opportunity to play here, develop my game and learn from the players here is very exciting for me. It's a massive Club. They don't get much bigger than Arsenal and I've always been a big fan.
"Growing up, Thierry Henry was one of my favourite players," he added.
"Some of the stuff he used to do. He used to score some amazing goals, he was quick and he was exciting to watch.
"He was always the star man on Match of the Day. The highlights were always of him and some of the goals he scored were fantastic."