The signing ceremony was chaired by Deputy Finance Minister Viroon Techapaiboon, and attended by other high-ranking officials from Thailand and the UK, including Secretary of State for Wales the Right Honourable Cheryl Gillan MP, and British ambassador to Thailand Asif Ahmad.
The Royal Mint won the bid at US$8.58 million, or Bt266.68 million.
The agreement reflected the close ties of the two nations, along with other relations on trade and investment, Mr Viroon said.
He noted the Royal Mint will provide assistance to Thailand on minting as well as exchange knowledge, technology, and training.
Thailand's Treasury Deparment in past years bought other types of coins from the UK's Royal Mint to circulate in the Thai economy.