He takes over from Barry Senft who has been executive director since the organization was formed 10 years ago from a merger among wheat, corn, soybean, oat and barley organizations.
Devitt came to Grain Farmers of Ontario from the Canadian Seed Trade Association where he was executive director.
He handled research projects and relationships and is currently vice president for strategic development.
GFO chairman Markus Haerle said Devitt faced competition from a strong group of international competitors.