The emergency services were called to Boclair Academy in Bearsden on Friday morning after a "strange smell" was detected in the building.
East Dunbartonshire Council said all pupils were safe and had been taken to nearby Killermont Primary School.
Boclair Academy was later declared safe after a leak from emergency lighting was identified as the source.
After the evacuation, arrangements had been made for pupils to sit their National 5 Modern Studies exam at Bearsden Academy.
However, the council later said the exam would take place as originally planned at Boclair Academy.
The school is expected to open again as usual on Monday.
Exams are set to go ahead as planned at a secondary school which was evacuated due to a chemical leak.