He will take up a coaching role with Harlequins, three months after becoming a player-coach.
"I realised that whether I'm playing or coaching, there was no possible way that I would be able to give 100 per cent to both of my roles at the same time," he told the club's website (www.quins.co.uk).
"I thought, why not grab the opportunity of becoming a coach with both hands, give it my best shot and feel privileged to be in a position to go out on my own terms after 12 great years as a player for Harlequins."
Easter won the first of his 54 England caps in 2007, playing in the World Cup final that year.
In 2015 he returned to international rugby after a four-year absence, scoring three tries against Uruguay in a World Cup match.
That made him the oldest hat-trick scorer in test matches.
(Reporting by Steve Tongue)
