Police were called to the scene, on Thepkrasattri Rd in front of a 7-Eleven store in Thalang, at 12:10pm.
The driver of the motorbike, named by police as “Danny”, 29, from Margate, England, was conscious and suffered only minor injuries, said Lt Col Sanit Nookong of the Thalang Police.
“But he was in a state of shock and was taken to Thalang Hospital,” Col Sanit said.
Danny’s passenger on the motorbike, who police named as “Sophie”, 41, from Blackpool, was dead at the scene.
Sophie was six months pregnant, Col Sanit confirmed to The Phuket News.
"They were not married, but they were partners and he was the father of her unborn child,” he said.
“Witnesses said that the motorbike was travelling in the left lane northbound and pulled out to drive around a parked car, and was struck by the truck,” Col Sanit said.
The woman was crushed under the wheels of the juggernaut, he added.
The driver of the truck, who initially fled the scene, has already surrendered himself to police.
He has been identified as Nattawoot Kimchue, 30, from Thai Muang in Phang Nga Province, north of Phuket.
Police have yet to confirm any charges over the accident.
* The Phuket News is withholding the victims’ names until it has been confirmed that the next of kin have been notified.