Leonardo 'Leo' Sanchez became trapped under the chair at the West Jordan Child Center after a member of the staff sat on top of it, accidentally suffocating him.
Danielle Sanchez said her son was playing with other children when he went underneath the chair to hide. The daycare worker then sat on the child-sized chair to read a story to the other children.
Police said the adult woman was unaware that Leo was underneath the chair and that the child's tragic death appears to be an accident. Leo was unconscious and wasn't breathing when he was discovered.
Staff believe Leo was underneath the chair for 10 to 15 minutes before they found him.
Authorities said investigation is ongoing.
The West Jordan Child Center has not yet commented on the incident.
Leo's death has devastated his family, where he was the third out of four children.
'I'm supposed to be planning his birthday party for next week and now I'm planning his funeral,' Sanchez said.