The officers, who examined footage from security cameras, identified the suspect as Natphat Sukprasong, 43, before nabbing her at her house and seizing 72 gold necklaces.
However, the owner of the shop, Aurora Design Co, said nearly half of the stolen jewellery was still missing. Only 68 out of the 130-baht weight of gold was retrieved.
Police say Ms Natphat, a resident of Ayutthaya's Bang Pa-in district, told them she buried all the gold ornaments. She was arrested before digging them up to sell, she said.
They say Ms Natphat, a former songthaew driver for Tesco Lotus at its Nawa Nakhon branch, raided Aurora gold shop on Dec 23 and made off with millions of baht worth of jewellery.
Police have charged her with robbery and illegal possession of a gun.