Officers conducting a routine inspection in Soi Saphan Hin stopped a vehicle driven by 43-year-old Panya Boonkaew and conducted a search at about 2am.
The search uncovered a .38-calibre firearm (serial number KorThor 5601348) along with 20 rounds of ammunition.
Authorities seized the weapon and ammunition as evidence before transferring the suspect to the investigation team for further legal proceedings.
No victims or property damage were reported in connection with the case.
The operation was part of routine inspections in the area under instructions by Phuket City Police Chief Pol Col Chatree Chueakaew, with the arrest report filed by Pol Lt Col Thanthurong Wutthiwong, Deputy Superintendent of Investigation, Phuket City Police reported.
Phuket City Police emphasised that routine checkpoints are part of ongoing efforts to ensure public safety and prevent illegal firearm possession in the province.