Are there nonstop flights from Bangkok (DMK) to Ubon Ratchathani (UBP)?

Yes. Thai AirAsia, Thai Lion Air, Nok Air fly this route. Flight time is about 1h 4m.

Bangkok → Ubon Ratchathani

Don Mueang International Airport (DMK) to Ubon Ratchathani Airport (UBP)・482 km

Nonstop flights available (3 airlines). Flight time about 1h 4m. Nonstop return flights also operate.

Times are estimated from distance. Check schedules, frequency and availability with the airline or a booking site.