Saguenay public security received a 911 call Saturday morning from a home on St-Jacques Street alerting them to the girl's death.
Jonquière is nearly 500 kilometres northeast of Montreal.
Upon arriving on scene, officers identified a number of potentially suspicious elements. They asked provincial police to step in to assist with the investigation.
"We’re looking to know if a criminal act was committed," said Const. Jean Tremblay of the Sûreté du Québec.
Investigators spoke with a number of witnesses, including the child's mother. No arrests have been made so far.
The body is being transported to Montreal, where an autopsy will be conducted to identify the circumstances surrounding the toddler's death.
Coroner Sylvain Truchon has been put in charge of the file.
"Like in all cases where a young child has died, the body is taken into the coroner’s custody. As in many cases, autopsies usually take place in a hospital or medical laboratory," Truchon said.