Police Region 5 commander Pol Lt-Gen Suthep Dejraksa said Chaliew Luecha, 54, and Suchin Malisa, 51, were arrested with about 100,000 pills of drugs and four kilogrammes of heroin.
The two men were driving separate pick-up trucks on their way to Bangkok but were stopped by police at a checkpoint in Lampang's Sobprab district.
During the search, Mr Chaliew claimed that he was a local reporter in Bangkok and vicinity areas.
Gen Suthep said, according to the investigation, the two were hired to transport the drugs from Chiang Mai to the capital with two cars.
Mr Suchin drove the first vehicle, followed by Mr Chaliew's car in which drugs were hidden in the car's tyres.