The Office of the Narcotics Control Board (ONCB) and Kanchanaburi police arrested Rojana Pongsakkachorn at a house in Sai Yok district.
She is a member of the gang led by Suchada Tuaypa, better known as Je Phen.
They also seized three bank books, eight cows, a bus, two cars, three motorcycles, seven guns, gold ornaments and 200,000 baht in cash. The total seizure had an estimated value 100 million baht.
Mrs Rojana was on the wanted list of the ONCB, its chief Pongsapat Pongcharoen said.
She was the sixth member of the network to be arrested by authorities.
Je Phen is believed to have fled to Thachilek in Myanmar to escape an arrest warrant issued by Ngao police in Lampang.
The warrant for her was approved after police seized 1.28 million methaphetamine pills and five kilogrammes of crystal methaphetamine in October 2012.
The ONCB said in a statement that the gang smuggled methaphetamine tablets from Payathonzu town in Myanmar.
The Myanmar town is opposite Sangkhla Buri district in Kanchanaburi.
Pol Gen Pongsapat said the drugs were distributed to agents in Kanchanaburi, Ratchaburi, Nakhon Pathom and Suphan Buri.
"We believe the drugs came from a production base in the area controlled by Karen opposite Sangkhla Buri district in Kanchanaburi province," he said.