His decision to call in and then approve the schemes after they were altered to increase the affordable housing element means construction can proceed on nearly 700 homes.
Haringey Council had rejected an application for up to 505 homes, including a 21-storey tower at Hale Wharf in Tottenham, over concerns that it would be too tall and would adversely impact Green Belt land.
The Allies and Morrison designed scheme for joint developer Muse and the Canal and River Trust will now start first phase piling this summer.
Likewise, an application for 186 homes in Palmerston Road in Wealdstone was also rejected by Harrow Council, as the 17-storey development was deemed too high.
Now Origin Housing Association can go ahead with its plans for the £15m project, which is being bid by Galliford Try and Keepmoat.
Khan said: “We’ve worked with the applicant on the Hale Wharf scheme in Haringey to increase the level of affordable housing and ensure the project will not encroach on our precious green belt, as was the case in earlier designs.
“The development at Palmerston Road in Harrow also offers a high level of affordable housing, which is particularly important as we move towards my long-term strategic target of 50% affordable.”