Samui police chief Pol Colonel Phaitoon Krachajang said Charnarongrak Somsri was arrested when he turned up at the Thailand Post office in Tambon Maenam to pick up his parcel on Thursday.
Police found 1,600 meth pills and 30 grams of crystal meth in the parcel.
He admitted that he ordered the drug from a seller in Bangkok’s Saimai district for reselling to youths on the island.
Police later searched his house and found a 9mm pistol and 20 rounds of ammunition.
Phaitoon said police planned the latest arrest after they apprehended a hotel worker and a student on training at the hotel for ordering marijuana via a parcel service for reselling to tourists on the island. The two told police that they had learned of the drug-ordering Facebook page from Charnarongrak.