Christopher Richardson told CBC his decision was not health-related, but refused to elaborate further, saying only that stepping aside for now was in the best interest of the board.
Richardson's voice shook with emotion Monday night as he read his resignation, a week after criticism erupted over a report calling for 19 school closures to save millions.
Vice-chair Janet Fraser will step in as interim chair for the Richardson until a vote June 24.
Earlier in June criticism erupted after the government released an audit that recommended school closures.
The Ernst Young report,commissioned by the Ministry of Education, recommended shutting 19 under-capacity schools to save $37 million a year.
Richardson told CBC he plans to take on new projects for now, but does not rule out returning to the VSB in the future.