Flights will also be added to the Bangkok-Trat (three a day) and Bangkok-Malé (five a week) also from March 31).
Additional frequencies will be added to flights between Samui and Phuket during the summer, the airline said, without giving details.
The airline recently launched a direct service from Bangkok to Vientiane and an additional service between Hong Kong and Samui.
Emirates, meanwhile, is preparing to launch a fifth daily non-stop service between Dubai and Bangkok.
From March 31 the Dubai-based airline Emirates will operate 35 flights a week between Dubai and Bangkok, plus a daily Airbus A380 service between Bangkok and Hong Kong, and a daily flight between Bangkok and Sydney, which connects on to Christchurch in New Zealand.
These services, along with the airline's Phuket flights, will take the number of weekly Emirates departures from Thailand to 56.