The two clubs agreed a fee of around £10 million for the Spaniard, who will be tasked with helping to fill the midfield void left by the departures of Cesc Fabregas and Samir Nasri from Emirates Stadium.
Arteta forced Everton’s hand by asking to leave as soon as he became aware of Arsenal’s interest, and afterwards claimed the chance to play in Europe’s premier club competition was one he was unable to pass up.
"It is a big opportunity for me and my family and I think it is the right time for me to take it," he told reporters.
"It is a big challenge, a different challenge, fresh for me and I want to see myself on the biggest stage, the Champions League.
"I am 29-years-old so I haven't got much time left to take a chance like this one. I think I have done my best for Everton.
"I always try hard, I have been as professional as I could and I was grateful for the support and the love that the club and the fans showed me."
Despite his excitement at joining the Gunners, Arteta admits he found it hard to leave Everton after six impressive seasons at the club.
"It is very difficult to say goodbye,” he told EvertonTV. “I still can't believe it but at the same time I think it is the right moment for everyone.
"That is the way football is, there is always a start and an end and today is the end of probably the best time of my career. I am never going to forget it.
"It has been crazy. I can't believe what happened, and the way it happened but as I said, that is part of football and I am going to be playing for another club soon.
"Obviously I am never going to forget what I have done here and what the people and this club have done for me."
Toffees boss David Moyes also expressed his sadness at losing Arteta, but admitted a lack of European football meant he was powerless to keep his star man once Arsenal declared their interest.
"Mikel indicated to me that he wished to join Arsenal if a bid came in," the Scot told the club's official website.
"I am very disappointed to lose him but the prospect of Champions League football was something I wasn't able to offer him."
