The 64-year-old is survived by wife and two sons.
Ahmed was rushed to a private hospital where he was declared brought dead, hospital sources said.
He was elected to the Lok Sabha from Uluberia constituency on a TMC ticket.
Ahmed had served as the Union Minister of State for Tourism in the UPA government headed by Manmohan Singh government.
He was elected to the West Bengal Assembly twice.
Chief Minister Mamata Banerjee condoled his death. "Shocked and deeply saddened at the passing of Sultan Ahmed sitting @AITCOfficial LS MP & my long term colleague. Condolences to his family", she said in a tweet.