Pol Maj Patiwat Yodkhawn confirmed that the Chalong Police were notified of the accident at about 2:30am.
One first responder at the scene told The Phuket News that it appeared the woman had missed a bend in the road, causing the Honda Zoomer X she was riding to hit the roadside tree.
The woman suffered severe head injury in the impact.
Although unable to locate a pulse, rescue workers attempted to revive her with CPR and rushed her to Vachira Phuket Hospital in Phuket Town, where she was pronounced dead on arrival.
“The victim’s friends said they went out to celebrate after she won a local Muay Thai fight and they were on their way home,” Maj Patiwat said.
“They said they offered to give her a ride back to the boxing camp where they were training, but she refused and left on her own on her motorbike,” he said.
The woman was not wearing a helmet at the time of the accident, Maj Patiwat said.
“We are waiting for doctors to confirm whether alcohol was involved before we conclude our investigation and we will contact the New Zealand Embassy and so they can notify her family today.” he added.