Manabendra Narayan Larma was born on 15 September 1939 at Maorum (Mahapuram) village, which is now drowned under the Kaptai Lake of Kaptai Dam. He belonged to the Chakma tribe, which inhabits the Chittagong Hill Tracts of Bangladesh and the neighbouring Indian states of Mizoram and Tripura. He graduated in 1963 from the Government College in Chittagong, completed his Bachelor of Education degree in 1968 from the Comilla Teachers' Training College and law degree in 1970 from the Chittagong Law College. Larma began working as a lawyer in the Chittagong District of East Pakistan. He became active in politics as a student, helping to organise a Hill Tracts students conference in 1963 and working for the rights of proper compensation of the people of the Hill Tracts displaced by the Kaptai Hydroelectric Project and uprooted from their homestead and villages. He was arrested on February 10, 1963 under the East Pakistan Public Security Ordinance by police. He was released after two years of incarceration on March 8, 1965.