The former Manchester United ace will take Alexis Sanchez’s old shirt – number 7 – after the swap deal involving the pair.
The move to see Mkhitaryan join Arsenal and Sanchez join Manchester United was announced last night.
Both players needed to pop to Liverpool to get their immigration papers signed off.
And both players have been training with their new team-mates today.
Mkhitaryan is cup tied for tomorrow’s League Cup match with Chelsea but could make his debut next week against Swansea in the Premier League with Arsenal missing out this weekend having been knocked out of the FA Cup.
And the Armenia star said he had always dreamed of playing for the Gunners.
He said: “I always loved the way that Arsenal played and the way that Arsene Wenger has managed the team. There have been a lot of young players, he’s managed them and they’ve done very well.
“Of course I was in love with the game of Thierry Henry. I loved the way he played – and maybe that was the reason to support Arsenal.”
He added: He said: “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.”
And Arsene Wenger hailed his arrival.
Wenger said: “Henrikh is a very complete player. He creates chances, he defends well, he can absorb distances and he’s very committed as well. I must say he’s a player who has all the attributes.”