Phuket City Police were alerted to the fire, in Phoonpon Soi 5, at 5:22pm.
Officers arrived to find firefighters already working to contain the blaze. The fire, which affected seven old shophouses, was brought under control by 6:15pm.
No injuries were reported from the fire.
Phuket City Police Chief Pol Col Pratuang Phonmana confirmed that investigators were working to determine the cause of the fire.
Firefighters and relevant agencies were on-site to assist and inspect the damage, which was confined to the affected properties.
Initial investigations have not identified any suspects or criminal activity linked to the incident, Phuket City Police reported.