Police and paramedics were called to the daycare in St-Basile-le-Grand — about 30 km east of Montreal — at around 12:20 p.m, when one of the workers discovered the baby was unconscious.
There were about half a dozen children at the daycare when the incident happened Friday afternoon.
Emergency responders tried to resuscitate the baby on site and then rushed her to hospital.
Officials at Charles Lemoyne Hospital declared she died shortly after 1 p.m.
Investigators spoke to the couple who own the daycare to determine the possible causes of her death.
Officials said it was still to early to know whether a factor at the daycare led to the baby's cardiac arrest or whether it was a medical issue.