The consultation includes proposed alterations to the London Plan under which planning obligations would be used to secure financial contributions from office developments in the Central Activities Zone and northern Isle of Dogs.
Mr Johnson said contributions from developers would come from section 106 planning gain and that he would consider applying the proposed Community Infrastructure Levy once it is implemented.
The s106 agreements will only be applied on new applications for additional office space above a 5,000 sq ft threshold in the two areas.
'Crossrail is vital'
Mr Johnson said: “Crossrail is vital to London’s continued competitiveness. I am committed to doing all I can to ensure it is delivered on time and on budget and these proposals are an important part of the funding package needed.”
News of the consultation came as a£350m funding deal with the City of London Corporation was announced.
The corporation has promised£200m towards Crossrail and will seek another£150m from businesses, of which it has guaranteed£50m.
Mr Johnson and transport minister Lord Adonis also announced the signing of a series of core funding and governance agreements that will underpin the project.
Funding arrangements for Crossrail currently involve the government, mayor and London businesses each contributing around a third of the expected cost.