The crystal meth has an estimated street value of 36 million baht.
Customs Department director-general Rakop Srisupaat said the suspect, identified as Frank Tuvi, 36, travelled from Nairobi.
Mr Tuvi was asked to go through security checks as customs officers thought he was acting suspiciously.
The Kenyan told officers that he came to Thailand to buy flat-screen televisions to resell them in his country.
He said the crystal meth was not his and another passenger probably switched his luggage by mistake.
The officers did not believe him and he is now being detained at the police Narcotics Suppression Division.
Mr Rakop said an increasing number of foreigners were recently being arrested at Suvarnabhumi airport for smuggling drugs. Cusomers officers had been instructed to keep a close watch on foreign arrivals who arouse their suspicions, especially people arriving from Africa.