The Hammers employed Twitter on Tuesday to say they are pleased to welcome back the 23-year-old for a different Premier League campaign at Upton Park.
He featured in 32 of West Ham’s Premier League games in the course of 2014/15 and can invest next season in east London under new manager Slaven Bilic.
The former Charlton trainee moved to the Emirates in 2011 and he told the West Ham website: “I’m seriously content to be back just after last year.
“It was a very good season for the club along with a very good season for myself.”
Jenkinson, who has created 57 appearances for the Gunners, played for England at the recent European Under-21 Championship finals.
And Arsenal boss Arsene Wenger mentioned of your deal: “We have the emergence of Hector Bellerin, we’ve (Mathieu) Debuchy, we’ve got (Calum) Chambers.
“We are a little congested in an area exactly where you do not obtain quite a few right-backs all over the world.
“He will continue his improvement with West Ham. I located that all are winners there – West Ham and Arsenal and Jenkinson.”