Born in Ban Pong district, Ratchaburi province, in Thai-Chinese and Mon family, Charnvit grew up in the neighbourhood of Phra Pradaeng, Bangkok Metropolitan Region.
He studied diplomacy and history at the Thammasat University in Bangkok, from 1960 to 1963, and graduated with Honours and the King Bhumibol Prize with a B.A.
He obtained his Ph.D. in Southeast Asian history from Cornell University in 1972, under the supervision of O. W. Wolters and David K. Wyatt.
He continued lecturing in the history department following his appointment as dean of the Faculty of Liberal Arts, Thammasat University.
He also held the post of secretary of the Social Sciences and Humanity Textbook Foundation in Thailand.