The letter argues that the level at which applications are referred to the mayor should be increased from 150 to 400 home and increased from 25m to 30m in height for sites next to the River Thames.
Johnson also suggests that a requirement to notify the mayor about plans to raise the height of existing buildings by more than 15m should be scrapped altogether.
Consultants have given a mixed response to the letter. "The mayor's planning powers always sat uncomfortably with the government's localism agenda. Removing a strategic pan-London oversight will leave many smaller proposals at the mercy of local level decision-making," said BNP Paribas Real Estate affordable housing director Anthony Lee.
"Initiatives put in place by the previous mayor, such as driving up affordable housing delivery and sustainability, may be at risk if local requirements are given priority in decision-making," he added.
However, Savills planning director Kieran Wheeler said: "I agree with this move. It will see a lot of small to medium-size projects given back to local authorities."
London Assembly Conservative group planning spokesman Steve O'Connell also welcomed the move. "The changes would mean less bureaucracy for developers and could speed up the planning process," he said.