His appointment as the executive vice president of Finance & Accounting was reportedly approved by the airline's board of directors.
Narongchai would join THAI on July 15. The airline's chief finance officer post has been left vacant for more than a year since the resignation of Wasukarn Visansawatdi on April 15, 2014.
It was reported that THAI is recruiting three new executive vice presidents to oversee the commercial operations, aviation and kitchen units.
THAI has suffered from fierce competition and structural weaknesses. In 2014, its revenue dropped from Bt21.2 billion a year ago, to Bt203.97 billion.