The woman was riding on a property west of Kingaroy when she was thrown from the animal.
She hit her head on the ground and was temporarily knocked unconscious.
The horse then rolled on the woman.
The RACQ CareFlight Rescue helicopter was tasked from the Clive Berghofer CareFlight Centre in Toowoomba at 2.30pm.
The woman was treated for a suspected head injury and flown to Toowoomba Hospital.
She travelled in a stable condition.