The duration of the contract has also not been revealed, reports the Bangkok Post.
Ishii’s first assignment will be an away friendly with his native Japan on Jan 1 in Tokyo.
This will be followed by the 2023 AFC Asian Cup finals in Qatar from Jan 12-Feb 10, 2024 and the second stage of the Asian qualifiers for the 2026 FIFA World Cup against South Korea on Mar 21 and 26.
FAT president Pol Gen Somyot Poompunmuang said: “I wish Masatada Ishii the best of luck and hope that he will bring success to the national team in the Asian Cup and World Cup qualifiers.”
After signing the contract, Ishii immediately had a meeting with Thai League Co officials to discuss ways to allow the national team players maximum possible time to train together ahead of their international assignments.
Ishii helped Kashima Antlers win the Luvan Cup in 2015, the J-League title and the Emperor Cup in 2016 and the Japanese Super Cup in 2017.
Under his supervision, Kashima Antlers also finished runners-up in the FIFA Club World Cup in 2016.
In 2019, he became the head coach of Samut Prakan City before moving to Buriram United with whom he recorded sweeps of all three domestic titles (the Thai League 1, FA Cup and League Cup) twice in 2021-2022 and 2022-2023 seasons.
Ishii takes over from previous coach Mano Polking who left the position on Nov 22.