The woman, who was flung to the side before the car lodged itself in the store in Palmerston St yesterday, suffered major leg injuries. Witnesses said her child suffered cuts and grazes. Both were flown directly to Nelson Hospital.
Emergency services were called at 4.30pm after "an older gentleman" lost control of his vehicle.
Westport Volunteer Fire Brigade chief fire officer Alan Kennedy said the woman was "very lucky that she wasn't directly in front of the car, as it could have been far more catastrophic".
The incident occurred in the car park, the vehicle narrowly missed the main window of the supermarket. It was heading straight for the shop itself but was halted by a beam in the building's main structure.
Mr Kennedy said a lot of people were shopping at the time, and customers were asked to remain in the store while the scene was taken care of, which took about an hour.
The Roa Mining West Coast Rescue Helicopter arrived from Greymouth at 5pm and flew the patients on to Nelson.
The driver of the SUV was tended to by St John personnel.
A police spokesman said inquiries were continuing.
