The man had flown from Luanda, Angola, with a stopover in Addis Ababa, Ethiopia, before arriving in Bangkok on Sept. 6. His final destination was Vientiane, Laos.
Authorities said he was flagged as a potential wildlife smuggler through advanced screening systems and intelligence data, Khaosod reported.
A search of his luggage uncovered five pieces of rhino horn weighing 6.86 kilograms, valued at around 6.9 million baht ($200,000), the Bangkok Post reported.
The arrest comes as Thai authorities intensify their crackdown on illegal wildlife trafficking.
Rhino horn continues to fetch high prices in some Asian markets despite a global trade ban. Southeast Asia has long been a favored transit hub for criminal networks smuggling contraband from Africa to buyers across the region.