Thai Smile (Bangkok Suvarnabhumi) operated its final services on December 31, 2023, with parent entity Thai Airways International (TG, Bangkok Suvarnabhumi) now taking over the LCC's flights and finalising the merger of the two airlines' operations. The final flights were roundtrip services out of Bangkok Suvarnabhumi Airport to Chiang Rai, Hat Yai, Krabi, and Khon Kaen.

Operating for eleven years, Thai Smile used a fleet of twenty A320-200s leased or subleased from Thai Airways to take over the parent entity's domestic operations and some regional flights. Thai Airways CEO Chai Eamsiri flagged the merger in early 2023, with the entire process taking less than one year. He said the merger and cessation of Thai Smile's operations is a strategic move designed to streamline operations and enhance service efficiency, including improving aircraft utilisation and contributing to the overall profitability of Thai Airways.

Since mid-2023, Thai Smile's A320-200s have been gradually repainted and returned to the Thai Airways' fleet. According to ch-aviation fleets advanced data, all but four aircraft had gone back to the parent airline by the end of 2023. Eamsiri says while Thai Airways has taken over Thai Smile's flights, any outstanding merger business, including transferring any remaining aircraft to the Thai Airways air operator's certificate, should be finalised by January 31, 2024.

The merger also sees Thai Airways return to domestic operations, which it stepped away from after the launch of Thai Smile. The flag carrier is back on nine domestic city pairs, including Bangkok Suvarnabhumi - Phuket; Bangkok Suvarnabhumi - Chiang Mai; Bangkok Suvarnabhumi - Khon Kaen; Bangkok Suvarnabhumi - Hat Yai; Bangkok Suvarnabhumi - Chiang Rai; Bangkok Suvarnabhumi- Udon Thani; Bangkok Suvarnabhumi - Ubon Ratchathani; Bangkok Suvarnabhumi - Krabi; and Bangkok Suvarnabhumi - Narathiwat.