Goodstuff, which won the business after a pitch against undisclosed agencies, has been briefed to work on communications strategy and audience insight. It will work alongside the other agencies on the Xbox roster, which include McCann Erickson, Universal McCann and the PR agency JCPR.
Goodstuff joins the roster as Xbox faces increasing competition from rival games consoles, the Sony PlayStation 3 and Nintendo Wii. However, according to Microsoft, a price drop in March resulted in a doubling of sales for the Xbox.
Ben Hayes, a partner at Goodstuff, will be responsible for the business. He previously worked on the PlayStation account at his former agency Manning Gottlieb OMD.
Stephen McGill, the head of gaming and entertainment at Microsoft UK, said: "Goodstuff was chosen as it understood our business very well and will bring challenging, energetic and creative thinking to the team."