The airline resumed the service on Thursday, with flight TG321 arriving in the capital at 12:30pm.
Based on passenger demand, Thai said it intends to add more flights in the coming months.
Passenger flights to Thailand had been suspended in March 2020 following the outbreak of the COVID-19 pandemic. But the Thai government has lifted entry restrictions for Bangladeshi nationals and other countries in recent months.
Thai Airways has been operating flights to Bangladesh for more than 50 years, providing air connectivity with many South-East and Far-Eastern countries.