The former chief minister was 80 and is survived by his wife Mira and daughter Suchetana.
A party official said Bhattacharjee died at around 8.30 am.
The veteran CPI(M) leader took over as the chief minister of
Bhattacharya lost the 2011 assembly election to Mamata Banerjee-led Trinamool Congress and the CPI(M)-led Left Front's 34-year-long rule in the state came to an end that year.
His tenure was marked by agitations over the acquisition of land for industries led by present Chief Minister
Bhattacharya stepped down from the CPI(M) politburo and central committee in 2015 and gave up membership of the party's state secretariat in 2018.
Over the last few years, he mostly stayed away from public programmes and remained confined to his two-room government apartment at Palm Avenue in south Kolkata.