The £19.1m helter skelter-like sculpture, designed by Turner Prize winning Anish Kapoor, will feature two public spaces at the top: a viewing gallery and a restaurant.
The spaces will be reached via huge lift, with visitors having the option of walking down the spiralling staircase to exit.
"We will use the facilities at the top of the Orbit for corporate entertainment during the Games and will set out a business plan to this effect," explained Johnson.
"We fully intend to keep the proceeds made by using the restaurant during the two weeks, so that the money we put in will be recouped immediately."
The London Development Agency is contributing £3.1m to the project, the rest being supplied by steel company ArcelorMittal.
It is yet unclear exactly how many people the viewing gallery and restaurant will hold.
Standing at a gigantic 115m, the Orbit is expected to be the tallest sculpture in the UK and will offer views across the entire 250 acres of the Olympic Park and London's skyline.
It will be situated in the southern part of the Olympic Park between the Stadium and Aquatics Centre and will open in time for the 2012 Games.
After completion, the Olympic Park Legacy Company will take ownership and run the visitor attraction.
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