The unnamed suspect was arrested at his apartment on Ram-Indra Soi 115 in Min Buri district on Tuesday morning.
Narcotics Suppression Bureau deputy commissioner Pol Maj-General Pornchai Charoenwong said the man had in his possession 426,000 ya ba pills (amphetamine), 1,320 bottles of Ecstasy (ketamine) and four grams of ice (crystal meth), as well as a gun.
Police tracked him down as the supplier of three drug users they arrested two weeks ago.
The Min Buri teen claimed he’d bought the drugs from members of the Wa hilltribe in Chiang Rai.
As well as reselling them online, he had retailers in Bangkok areas under the jurisdiction of Metropolitan Police Bureaux 3 and 4.
He is charged with possessing drugs with intent to sell and having a gun without a permit.