Authorities found five pickup trucks carrying nearly 100 Rohingya before dawn on Sunday in the Hua Sai district of Nakhon Si Thammarat province on the Gulf of Thailand.
"There were total 98 Rohingya. Of them, one woman aged around 20 years old died from suffocation while travelling," provincial police commander Kiattipong Khawsamang told AFP.
"The truck was crowded and she also had not eaten," Kiattipong said, adding the group was travelling from Phang Nga province on the western seaboard.
Two of the pickup drivers have been arrested on suspicion of people-trafficking, he added.
Thai authorities will now process the group to establish whether they were being trafficked by smugglers through Thailand.
Authorities have in recent weeks discovered scores of other migrants who fled dire conditions in Myanmar, taking advantage of the slightly calmer winter waters in the Andaman Sea to head south.
On January 5 police detained 53 migrants from Myanmar -- the majority of them Rohingya -- in Phang Nga province, a hub for boatpeople being transported on to mainly Muslim Malaysia.
Thousands of Rohingya have fled deadly communal unrest in Myanmar's Rakhine state since 2012.
AFP