The speed cameras have been installed at Thurgood Marshall, Boardview-Thomson, Olympic View, and Gatewood.
The cameras are active only during school hours and drivers will be warned of the 20 mph speed limit by flashing yellow lights.
"Those little ones need your help to make sure they're safe," said Teresa Wippel with Seattle Public Schools. "Nobody wants to have an accident happen"
Police are also using a mobile speed van to catch speeders near schools that don't have dedicated cameras.
The city says the goal of the program is not simply to issue tickets, but to improve safety and reduce collisions near schools.