The accident occurred at about 7:50am near the Poon Tra Nok U-turn point on the outbound side of the road, Thalang Police reported.
The victim, named by police as Rattanaporn Bunchu, a local resident of Srisoonthorn, was pronounced dead at the scene.
Police said the truck, a Hino bearing Phuket licence plates, was being driven by 31-year-old Narong Chumkaew from Songkhla.
The vehicle reportedly lost control before colliding with Ms Rattanaporn’s motorcycle and dragging it into a roadside power pole, which was also damaged in the crash.
Forensic officers and medical examiners conducted an initial examination at the scene, after which Ms Rattanaporn’s body was taken to Thalang Hospital. Her relatives in Chumphon have been notified.
The truck driver was taken into custody while the investigation continues, Thalang Police confirmed.