Addressing the opening ceremony, Hong Kong's Chief Executive Carrie Lam said the establishment of the Bangkok office is a clear and compelling statement of the importance of Asean to Hong Kong.
The Bangkok office is the third ETO established by the Hong Kong Special Administrative Region in the Asean region after Jakarta and Singapore.
Lam said she expected the office to play the role of facilitator to connect businesses and organisations between Hong Kong and Thailand, and serve as a catalyst to take the cooperation of both sides to new heights and fresh directions.
Somkid Jatusripitak, Thailand's deputy prime minister in charge of the country's economy affairs, said Thailand aims to use Hong Kong as a gateway to China's Guangdong-Hong Kong-Macao Greater Bay Area.
He said Thailand expected more investment from the Greater Bay Area.
Lam also met Thai Prime Minister Prayut Chan-o-cha on Thursday and Foreign Minister Don Pramudwinai.