Bangkok Airways will launch new Bangkok-Khon Kaen and Bangkok-Mae Sot services, while Nok Air will operate a Chiang Mai-Mae Hong Son route.
The new routes will run from March 28 to October 30 as part of the summer flight schedule.
The new Bangkok-Khon Kaen service will offer 14 flights per week while the Bangkok-Mae Sot route will offer 21 flights per week. There will be three flights per week on the Chiang Mai-Mae Hong Son route.
Meanwhile, the department said that Krabi, Surat Thani and Hua Hin airports were now ready to receive international flights.