Authorities had been searching for the 49-year-old Thai man since last year, when they issued a warrant for his arrest after seizing a Bengal tiger cub during a separate operation.
Police believe the network is buying tigers and selling them to purchasers, mainly in China, said Chanadda Thanikulap of the Freeland Foundation, an anti-trafficking group based in Thailand.
The suspect was arrested on Saturday in north-eastern Thailand and is being held in Bangkok, police said yesterday.
Wildlife experts say the number of tigers in Asia has plummeted over the years due mainly to habitat loss and poachers who sell their skins and body parts to booming medicinal and souvenir markets, mostly in China. Conservationists say the government needs to do more to eliminate trafficking networks.