Police called to the residence about 2:30 a.m. Sunday said the girl has a "possible stab wound," the Detroit Free Press reported.
An autopsy is pending.
Police haven't released the identities of the mother or the girl.
Two other children lived in the apartment.
A police spokeswoman said authorities are trying to determine if the mother had any involvement in the girl's death.
A resident of the apartment building told the Detroit News she saw the girl lying on the living room floor as neighbors administered cardiopulmonary resuscitation and tried to stop bleeding from a stab wound to the girl's abdomen before the arrival of emergency workers.
The resident said the mother, who was seated on a sofa, kept pushing at the girl's body with her feet.