The fire broke out after 7 p.m. Aerial television footage showed the flames against a backdrop of spires along the roof of the building.
Firefighters had contained the blaze before 10 p.m., university officials said.
The building houses human resources, cashier services, the sociology department and campus ministry.
The Sisters of the Congregation of Divine Providence founded the university in 1895, according to the school's history on its Web site. The school has offered classes since 1911, initially only for women.