Narcotics police acting on a tip-off stopped Adelina Ntshebleng Lephutha Ononiwu, 31, at Suvarnabhumi Airport on Monday after she arrived from the Kenyan capital and was waiting for an onward flight to Cambodia.
Police found the drugs -- also known as "ice" -- in three bags hidden in a secret compartment in her luggage, they said. The haul has a street value of $80,000 in Thailand.
"She said she was hired by a Nigerian man to deliver the luggage to Phnom Penh," Colonel Pornchai Charoenwong of the Narcotic Suppression Bureau said.
"He paid her 24,000 baht ($760) and said she will get a further 200,000 baht when the job was completed," he said, adding she started her journey in Benin, West Africa.
Ononiwu was charged with drug trafficking, which carries a death sentence in Thailand, although executions are rarely sanctioned.
Thailand, along with other countries in the region, has seen a marked increase in seizures of methamphetamine as the world opiate trade declines.
A Malaysian woman was arrested on June 6 at the airport with 4.8 kilos of crystal methamphetamine after she arrived from Benin, one of the largest seizures of the drug from an individual smuggler.