The all-clear was sounded by Nottawasaga OPP nearly two hours after Angus Morrison Elementary School was evacuated on Friday because of a bomb threat.
Police responded to the Essa Township school around 11:30 a.m.
A hold and secure was put in place.
Staff and students were evacuated from the building and numerous roads in the area were closed.
A search of the school and property did not result in locating any explosives. The school returned to business just after 1 p.m.
Police continue the investigation.