Boris Johnson has taken over a planning application to redevelop the Saatchi & Saatchi building in central London after the local council refused permission for the scheme.
Earlier this month Camden Council refused developers Derwent London permission for the project which includes plans for office and retail space and 55 flats.
The Mayor has exercised powers given to him in 2008 to take over any planning application which has an impact for London as a whole.
City Hall has defended the decision to sideline the local council on the grounds that the scheme will raise £1.6m for the Crossrail scheme and create new jobs.
In a statement the Mayor said: “These buildings have been home to some of the most creative and innovative minds for the last 40 years, making the area an internationally recognised hub for the global advertising industry.
“Redeveloping this prime location will contribute to the competitiveness of London’s wider economy bringing with it new jobs and business.
“This proposal clearly meets the test of a planning application of major significance to London and I therefore believe it is right that I scrutinise it in greater detail.”