The crash happened at the Mill Green Island next to the West Midlands Designer Outlet in Cannock at around 9.45am on Friday.
An air ambulance was sent to the roundabout, which connects the A460 Eastern Way and the A5190 Lichfield Road
The female biker was given specialist trauma care at the scene before being flown to Royal Stoke University Hospital for further treatment.
Nobody else is thought to have been injured in the crash.
A West Midlands Ambulance Service spokeswoman said: "Crews arrived at the scene to find the motorcyclist, a woman, with serious injuries.
"She was given specialist trauma care at the scene before being flown to Royal Stoke University Hospital, with treatment continuing on route."
Two ambulances, a paramedic officer, and the Midlands Air Ambulance from Cosford attended the scene.
Staffordshire Police has been contacted for a comment.