Thai Airways International plc (Thai: บริษัท การบินไทย จำกัด (มหาชน)) is the flag carrier airline of Thailand. Formed in 1961 as a joint venture between SAS and Thai Airways Company, the airline has its corporate headquarters in Vibhavadi Rangsit Road, Chatuchak district, Bangkok, and primarily operates from Suvarnabhumi Airport. THAI is a founding member of the Star Alliance. The airline is the second-largest shareholder of the low-cost carrier Nok Air with a 8.91 percent stake (2021), and it launched a regional carrier under the name Thai Smile in the middle of 2012 using new Airbus A320 aircraft. In 2023, it was announced that Thai Smile would be merged back into Thai Airways.

Operating from its primary hub at Bangkok's Suvarnabhumi Airport, THAI currently serves 51 international and 10 domestic destinations using a fleet of 79 aircraft consisting of wide-body and narrow-body aircraft from both Boeing and Airbus with 90 aircraft on order as of November 2025, with plans to increase its fleet to 143 aircraft by 2029. Currently THAI's route network is dominated by flights to cities in Europe, Asia and Oceania flying to 30 countries as of March 2025 including 9 domestic routes.

THAI Airways is a member and one of the five founding members of Star Alliance, which was founded on 14 May 1997.

Thai Airways International was founded in 1960 as a joint venture between Scandinavian Airlines System (SAS), which held a 30 percent share of the new company valued at two million Thai baht, and Thailand's domestic carrier, Thai Airways Company (Thai: เดินอากาศไทย). SAS provided operational, managerial, and marketing expertise, with training aimed at building a fully independent national airline in the shortest possible time. Thai nationals were gradually able to assume full managerial responsibility and the number of expatriate staff duly decreased, with expatriates accounting for less than one percent of staff based in Thailand in 1987.

The airline's first intercontinental services using Douglas DC-8s started in 1971 to Australia, and then to Europe the following year. A number of the larger Douglas DC-10 wide-body tri-jets was acquired in the late-1970s. Services to North America commenced in 1980.

On 1 April 1977, after 17 years of capital participation by SAS, the Thai government bought out the remaining 15 percent of SAS-owned shares and Thai became a state owned enterprise of the Thai government. As of 22 May 2020, the Thai Ministry of Finance is no longer the majority shareholder, having reduced its holding to 47.86 percent from 51.03 percent.

In 1979, the carrier received its first cargo aircraft which is a Douglas DC-8-62AF used for flying between Bangkok and Karachi, Frankfurt, Copenhagen, Hong Kong as well as a flight from Copenhagen to Paris.

On 6 December 1987, services to Auckland in New Zealand were inaugurated. On 1 April 1988, then-Prime Minister Gen. Prem Tinsulanonda, merged the international and domestic operations of the two companies to form the present company, Thai Airways International, to have a single national carrier. On 25 June 1991, the reconfigured company listed its shares on the Stock Exchange of Thailand and offered them to the public. The Thai public offering of shares is the largest ever undertaken in the country.