The Icelandic keeper, 28, played just six times in all competitions for Arsenal, largely in the Europa League during the early part of Mikel Arteta‘s tenure.
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But Arsenal fans will remember him for his disastrous performance against Manchester City during a 4-1 Carabao Cup defeat in December 2020.
City opened the scoring after just 125 seconds when Runarsson came out to punch the air instead of the ball – giving Gabriel Jesus an open goal to head into.
His night would get so much worse when he punched a Riyad Mahrez free kick that was straight at him into his own net.
The keeper did not cover himself in glory for the next two as City romped to a 4-1 victory to see them through to the next round.
Runarsson signed for Arsenal in the summer of 2020 from Ligue 1 side Dijon but only spent the 2020-21 season at the club.
Brighton goalkeeper Mat Ryan was signed in January, six months after Runarsson’s signature to demote the Icelandic keeper to third-choice.
He spent the subsequent season out on loan at Oud-Heverlee Leuven in Belgium before joining Turkish side Alanyaspor last season.
Runarsson will reach the end of his contract by the time his loan spell finishes, although Football London indicates Arsenal have the option to extend his deal by another 12 months.
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Runarsson’s loan to Championship club Cardiff represents a second chance for him in the English football pyramid after spending the last two years out on loan in Europe.
The keeper will compete with Ryan Allsop and Jak Alnwick for a spot in the team – with Allsop being the more regular starter last season.
On joining Cardiff, Runarsson said: “I’m very happy to get the deal over the line. It took some time, but I’m pleased to be here.
“I spoke to Gunnars [Aron Gunnarsson] before signing and the first thing he said was ‘go’ and that he loved it here. The manager also spoke to me about the playing style, what he wants from me, what he wants from the team and how he sees my role within the team.
“He saw me play in Turkey when I was on loan there, so it’s good that I’m coming to play for a manager that knows me and knows my qualities.
“I’m really excited to play in front of the fans. Seeing the stadium, I can feel the atmosphere in the air, so I’m looking forward playing in front of fans.
“When I signed for Arsenal, it was during Covid, so I didn’t get to experience British football with the fans, so I’m excited to play in that atmosphere.”
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