Runarsson, 25, has joined the Gunners on a four-year deal for a reported fee of €1.5m.
The shot-stopper has taken the number 13 shirt at Arsenal.
Welcome to The Arsenal, Alex Runarsson 🔴
— Arsenal (@Arsenal) September 21, 2020
He will provide competition to Bernd Leno at the Emirates, replacing Emi Martinez who signed for Aston Villa.
In his first interview with the Arsenal website, Runarsson expressed pride at joining the London club.
“I’m just extremely happy, extremely proud, it is a big day for me and my family. I can’t wait to get started!” he said.
“It is one of the biggest clubs in the world – they’ve won the Premier League 13 times, the FA Cup 14 times, it is a huge club and obviously playing in the Premier League as well, it is a win-win situation.
“I know it is going to be a lot of hard work, but I am ready to do everything I can to get the most amount of minutes as possible.”