The England midfielder sealed a £35m move from north London to Liverpool late in the transfer window.
He snubbed Chelsea to join Jurgen Klopp's side and has admitted it was the hardest decision of his life to leave Arsenal.
But he thinks Liverpool is the perfect fit for him at this stage in his career.
And after completing the move he says he simply had to do it.
Oxlade-Chamberlain told The Times: "Saying thank you and goodbye to the manager was definitely very difficult.
"It was the hardest decision I've ever had to make.
"I was there six years, good and bad times, shared a lot of experiences with great people.
"I want to thank the Arsenal fans who've always supported me.
"But I can't apologise for my decision to leave.
"I want to get more out of myself.
"I felt the main thing was taking myself out of my comfort zone.
"That's why Liverpool shouted out for me.
"You can see how the team play, how he [Klopp] instils that intensity in the players. I feel that kick up the backside would be good for me."
