Mkhitaryan has made the switch to the Emirates Stadium as part of the deal which has resulted in Alexis Sanchez joining Manchester United, but the Armenian international has been a long-time admirer of the Gunners.
In an interview with UEFA in 2009, Mkhitaryan said that he was keen to sign for the North London outfit at some stage of his career, and the playmaker has got his wish after penning a long-term deal with the club.
The 29-year-old told the club's official website: "I'm very happy that we could finish this deal and I'm very happy to be here.
"It's a dream come true because I've always dreamed of playing for Arsenal. Now that I'm here, I'll do my best for this club to create history."
Mkhitaryan is likely to make his debut for Arsenal during the Premier League game with Swansea City on January 30.