Prime Minister Prayut Chan-o-cha will attend a US-Asean special summit from May 12-13, said Deputy Prime Minister and Foreign Minister Don Pramudwinai.
Thailand ranks among the 10 members of the Jakarta-based Association of Southeast Asian Nations (Asean).
Mr Don said the summit was originally due to be held last October but some of the bloc's leaders as well as US President Joe Biden were not available at the time, prompting it to be postponed.
The rescheduling had nothing to do with the Russia-Ukraine conflict, he said, adding Gen Prayut received his invitation before the invasion began. He said the current itinerary does not include bilateral talks with Mr Biden.
Asean leaders also plan to meet with the European Union this year or early next year at the latest, Mr Don said.
The US Embassy in Thailand on Tuesday confirmed that Mr Biden will host Asean leaders in Washington, DC for the summit.
The aim is to show the United States' commitment to Asean, promote the country's key role in delivering solutions to the region's challenges, and commemorate 45 years of US-Asean relations, it said.
It will build on Mr Biden's announcement last year of US$102 million (3.4 billion baht) in new initiatives to expand Washington's engagement with Asean on Covid-19 recovery and health security, the climate crisis, economic growth, promoting gender equality and deepening people-to-people ties.
The Biden-Harris administration wants to serve as a strong, reliable partner in Southeast Asia, it said. Washington's shared aspirations for the region will underpin its commitment to advance a free, open and secure Indo-Pacific, it added.
