PrettyGreen will manage the EA Games label, which focuses on action adventure, and EA Maxis, which produces simulation titles.
The agency will oversee all launches, with Need for Speed Most Wanted, one of its biggest titles, Medal of Honor Warfighter, and The Sims: Supernatural 3 expected to take place during 2012.
An ongoing press office, to boost knowledge and sales of all titles, and bespoke creative campaigns to support launches form part of the brief.
Clifford French will continue to look after the EA Sports label, which includes the FIFA, Tiger Woods and SSX titles.
EA was the best selling games publisher both in the UK and globally in 2011, and is the third largest company by revenue, after Nintendo.
Activision, the second largest, appointed The Red Consultancy in May following a shake-up of an account that is thought to be worth £500,000 - believed to be the gaming industry's largest for PR.
Its Call of Duty games continue to command the top sales in the industry, but the firm still lags behind EA in total game sales.
Heading the PrettyGreen team is Sarah Henderson, group account director, supported by Chris Grabowski, account director.
They will report to James Bruce, PR manager for games, and Bryony Benoy, PR manager for Maxis, overseen by head of PR Shaun White.
White said: ‘We saw a lot of agencies pitch, but felt that PrettyGreen offered us a fantastic mix of creativity and passion, which we found so infectious. We're excited about embarking on a new journey with an agency that will challenge us internally and help us really push the boundaries.’
PrettyGreen founder Mark Stringer said he was ‘honoured’ by the appointment: ‘EA is one of those dream brands that's on every agency’s wish list. It's a great win for the team and we feel somewhat honoured that EA has chosen PrettyGreen and are as excited as we are with the campaigns that we have developed.’