The girl was hit by a vehicle travelling south on the one-way system about 4pm.
Sergeant Chris MacAulay said the year 12 pupil was transported by ambulance to Dunedin Hospital with leg injuries.
Part of SH1 and Dundas St were temporarily closed while the girl was treated at the scene.
Police were investigating whether the pedestrian or the driver of the vehicle had the right of way.
Sgt MacAulay said the incident served as a timely reminder to pedestrians to make sure they were seen by motorists before walking across roads, regardless of whether they had the right of way.