Thai Airways International will start regular flights between Suvarnabhumi Airport in Bangkok and Haneda, Tokyo's domestic airport which is opening up for international services on 31 October.
The new route is expected to be popular with leisure and business travellers due to Haneda's proximity to central Tokyo.
Thai will be offering daily flights on the route on its Airbus A330-300 aircraft, says the airline.
Bangkok-Tokyo Haneda will be an additional service between Thailand and Japan for Thai, which will be maintaining its current two Japanese routes, it adds.
The Thai flag carrier currently operates three flights a day between Suvarnabhumi and Narita, Tokyo's main international airport, and twice daily services between Suvarnabhumi and Kansai International Airport in Osaka, using Boeing 747-400 and Boeing 777s.