Born in Siliguri (North Bengal) in 1949, he completed his graduation in Commerce from the University of North Bengal.
Ashok Bhattacharya started his political career as a corporator in Siliguri Municipal Corporation. He became the chairman of Siliguri municipality in 1987 and remained as the chairman till 1991. He was elected to the West Bengal Legislative Assembly from Siliguri (Vidhan Sabha constituency) as a CPI(M) candidate for the first time in 1991. He is a five-time MLA of West Bengal Legislative Assembly from Siliguri. He won elections from Siliguri in 1991, 1996, 2001, 2006 and 2016.
In 1996, he became the Minister for Urban Development and Municipal Affairs in the Left Front government in Bengal under chief minister Jyoti Basu. He also continued as cabinet minister under chief minister Buddhadeb Bhattacharjee till 2011 when the CPI(M)-led Left Front was defeated by Mamata Banerjee's All India Trinamool Congress (AITC).
In 2011 West Bengal Legislative Assembly election, Bhattacharya lost to TMC candidate Rudra Nath Bhattacharya in Siliguri. But he returned to power from his home constituency, Siliguri, again in 2016 West Bengal Legislative Assembly election beating TMC candidate and former captain of Indian National Football Team Bhaichung Bhutia.
In May 2015, Ashok Bhattacharya became the Mayor of Siliguri Municipal Corporation after the Left Front won the municipal election in Siliguri.
