Manchester-based With Reflex Group (WRG) won the contract to design, produce and manage the event, called by Prime Minister Gordon Brown to address the world economic crisis, at Excel London in April.
Facilities included a fully equipped media centre for 3,000 journalists, more than half a mile of meeting facilities, delegation offices, lounge and dining areas, plus 200 broadcast and radio edit booths.
The agency has since received correspondence from No.10 and The Foreign and Commonwealth Office praising its work.
A statement from the former read: "An amazing, incredible summit, you and your team did quite a stunning job."
While the latter commented: "As always a pleasure to work with you and your superb team... another outstanding achievement."
The event marked the first European summit attended by US President Barack Obama, who widely proclaimed it to be a huge success and very well organised.
Event reported earlier this year how WRG controversially choreographed the handover of power from Tony Blair to Gordon Brown in 2007.
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