The Rituraj Hotel, which had 88 guests when the fire broke out, is located in a congested business district of central Kolkata.
About a dozen people suffered burn injuries and are undergoing treatment.
Building fires are common in India due to a lack of firefighting equipment and a routine disregard for safety regulations.
Eyewitness Nanda Mondal, who runs a construction company, said he saw plastic panels covering the building that appeared to have “fuelled the fire”.
“A man died after he tried to climb down a rainwater pipe,” said Mondal, 64.
