He was born on 17 September 1955, in Suphan Buri Province, and entered the monastic life as a novice at the age of 12. In 1976, while still a novice, he completed the highest degree of traditional Pali Studies in Thailand, Pali Grade IX. In the same year, His Majesty, the King of Thailand, sponsored his higher ordination in the temple of the Emerald Buddha.

After receiving his Doctorate, he lectured for a time at MCU. In 1986, the Thai Sangha Supreme Council posted him to the Thai Buddhist Temple in Chicago, U.S.A. as a Dhammaduta (missionary monk). He returned to MCU to serve as Director of the Academic Division and later served as the first Dean of the Graduate school, Deputy Rector for Research and Planning, and Deputy Rector for Academic Affairs. His Holiness, the Supreme Patriarch of Thailand, made him Rector of MCU 1997, and a year later appointed him Ecclesiastical Governor of Region II covering the provinces of Ayutthaya, Saraburi, and Ang Thong.

Apart from Sangha administrative work, he is one of Thailand’s scholar monks and the author of more than 60 books on Buddhism and philosophy. His published works in Thai and English include, among others, History of Greek Philosophy; A Buddhist Approach to Peace; Buddhist Morality; Buddhist Worldview; and International Recognition of the Day of Vesak.

Previously known as Phra Maha Prayoon Mererk, Phra Methithammaphon, Phra Rajavaramuni, and Phra Thepsophon, he was given the new title of Phra Dharmakosajarn by His Majesty, the King of Thailand, on December 5th, 2005 in recognition of his continuing contributions to the Sangha and the broader society.