Police officers apprehended Supanuch Hongsaglai, 28, at The Mall Bang Kapi's parking lot after they were tipped off that people were handing over illicit drugs on the ground floor of the building, said Metropolitan Police Bureau chief Kamronwit Thoopkrachang.
Ms Supanuch told police that she had been asked to deposit boxes with the bag storage service at the shopping mall and give the claim tags to clients so they could pick them up. She said she was helping a close friend who told her she was delivering water filters.
Pol Lt Gen Kamronwit said officers then examined a box at the deposit counter and found a large quantity of ya ice inside.
The woman said she had done this twice before her arrest. She insisted she was not paid any money and that she had no idea what was inside the boxes.
Police charged the woman with possession of illegal drugs.
Meanwhile, a man with 78,000 methamphetamine pills, or ya ba, with an estimated street value of around 23.4 million baht was arrested in Wiang Sa district in Nan province.
Police intercepted a bronze pickup truck driven by Chuchai Suebsakwong, 54, and found 39 bundles of ya ba hidden in a black plastic bag on the back seat of the vehicle, said Pol Maj Gen Narongchai Wongsamee, commissioner of Nan provincial police.
As officers were conducting the search, Mr Chuchai attempted to flee but only got 50 metres before policemen caught up with him.
The suspect confessed he was hired by a man named Lao-ja Sae-warng in Chiang Rai's Chiang Khong district. He was to smuggle the drugs from Chiang Khong to a client in Ayutthaya province, whose name he does not know, he said.
Mr Chuchai said he received 20,000 baht for the job and was promised another 30,000 baht when he completed the delivery.
Police have charged him with possession of illegal drugs with the intent to distribute, and took him into custody at Wiang Sa police station.