A university spokeswoman said a small, smouldering fire was detected in the backstage roof/ceiling area of the College of Education Auditorium in Union St about 8.15am.
About 30 people were evacuated from the main building and a further 32 people from the neighbouring Otago University Childcare Association College Centre.
The fire was likely linked to work being done by contractors installing a new roof and fire sprinkler system in the auditorium, she said.
Due to lingering odours, classes in the auditorium and neighbouring drama centre were cancelled yesterday, but were expected to resume today.
A Fire and Emergency New Zealand spokesman said four crews from Dunedin Central, Willowbank, and Roslyn were initially called to the scene.
Upon arriving and seeing smoke, they called for additional resources from Dunedin Central, including the command unit.
The fire was extinguished by 9.30am.