The Manchester-based agency won the through-the-line business after a four-way pitch, overseen by the AAR.
The appointment is part of Gamestation's drive to raise awareness of the brand and increase its presence on the high street against competition from HMV and Game.
David Bell, the chief executive of CheethamBell, said: "Gamestation is an innovative and exciting retailer to be working for. It is clear that creative communications will be key to its future brand development and we are looking forward to working with the team at Gamestation to assist in its growth."
Martin Gibbs, the commercial director at Gamestation, said: "CheethamBell stood out because of its achievements for other high-profile brands and retailers.We were impressed by its levels of strategic thinking, creative ideas and true understanding of our target market."