The foundation of the party was declared by Kanu Sanyal at a mass meeting in Calcutta on 22 April, Vladimir Lenin's birthday.

[2] The CPI (ML) was formed by the radicals within the Communist Party of India (Marxist) (CPM) who grew concerned by the increasingly parliamentary character of its politics.

[3][4][5] According to Pradip Basu in his book Towards Naxalbari (1953-1967): An Account of Inner-Party Ideological Struggle:[6][7] "There were two nuclei of radicals in the party organisation in West Bengal.

According to Basu, due to the prevailing political climate of youth and student rebellion it was the 'actionists' which came to dominate the new Maoist movement in India, instead of the more theoretically advanced sections."

It occurred in Naxalbari of Siliguri subdivision, Darjeeling district under the leadership of communist leaders like Charu Majumdar and others who later became the part of CPI (ML).

In 1972, frail and broken Majumdar died of multiple diseases in police custody; after his death a series of splits took place during the major part of the 1970s.

Only C.P.I (M-L) faction led by Mahadev Mukherjee follows Charu Majumdar's concept of armed revolution and annihilation, whereas others have condemned the excesses of the sectarian epoch.