The woman, aged around 60, died on the spot and police are investigating the circumstances of the accident, said a report on the Corriere del Ticino newspaper.
The car, which had been parked in a courtyard, rolled down the street at speed, hitting the woman as she was walking up, the report said.
Police have not yet established why the parked car, a small red Peugeot, began moving of its own accord down Chemin du Levant, newspaper 24 Heures reports.
The footpath beside the site of the accident was closed off due to roadworks, the paper said.