Exodus Tyson was found at the family's Phoenix, Arizona, home on Monday morning with a cable attached to the machine wrapped around her neck.
She was immediately taken to a nearby hospital, where she was placed on life support. However, police have now confirmed that she was pronounced dead just before noon yesterday.
In a statement, the Tyson family said: "There are no words to describe the tragic loss of our beloved Exodus.
"We ask you now to please respect our need at this very difficult time for privacy to grieve and try to help each other heal."
Officials have speculated that the child was playing near the treadmill when she accidentally slipped her head through a looped cable which then acted as a noose.
Former heavyweight boxer Tyson was in Las Vegas on business at the time but returned home to Arizona when he was informed about the incident.
A family representative has since told PA that no funeral arrangements have yet been made.