Veteran Congress MLA Gyan Singh Sohanpal died at the SSKM hospital in Kolkata, Congress sources said.
He was 92 and a bachelor.
Fondly called "Chacha", Gyan Singh was admitted to the hospital with old age-related problems.
Gyan Singh who enjoyed immense respect among politicians cutting across party lines, was elected to the state assembly 10 times.
He was also a former minister in the Congress government in the state.
He had contested last year's assembly election in the state but was defeated.
West Bengal chief minister Mamata Banerjee condoled his death and said "We have lost a veteran legislator".
"Saddened at the passing of Gyan Singh Sohan Palji. We have lost a veteran legislator. My condolences to his family & friends", she said in a tweet.
"He was a very senior member of the West Bengal Assembly. Tomorrow, the Govt will give his mortal remains a gun salute", she said.
