The vast two-storey restaurant will serve up to 1,200 customers an hour and sell £3million of fast food during the Games.
At 3,000 sq ft the building, next to the Olympic Stadium, is bigger than the current largest McDonald’s, in Moscow.
The Russian restaurant will regain its title on September 9, however, when the London branch is bulldozed after the Paralympics closing ceremony.
It includes 20 till points and 1,500 seats.
It is one of four branches in the park, including two open to the public, one for the athletes and officials in the Olympic Village and one at the press centre.
Altogether they will serve 1.75million meals in 29 days, with Britons accounting for an estimated 85 per cent of customers.
The main restaurant will offer some of the best views across the Olympic Park from its first-floor balcony, which can seat 150 customers.
It will be staffed by 500 of its top-performing employees from 85,000 in the UK, with 200 on a shift at any one time.