First Steps for Families aims to make housing affordable to residents of the city who might otherwise be trapped indefinitely in rented accommodation.
The first 250 homes are planned for delivery by next summer, which could keep London builders busy with their bricklayers tools over the coming months.
However, the work is not due to stop then, with a further target in place of 1,000 properties to be completed over the next three years.
Mr Johnson says: "Many Londoners dream of being homeowners but are thwarted by the colossal property prices in London.
"My overriding ambition is to make the capital a city of opportunity and choice."
Along with the delivery of affordable housing, Mr Johnson has also outlined plans to make the capital's streets cleaner and safer, with better transport links.
Posted by Ryan Gilbert