The body of the two-month-old baby girl missing from her home in Beliaghata area of the city was found in a manhole near her residence, police said on Monday.
The mother was arrested for allegedly killing her baby and dumping the body in the manhole, a senior officer of Kolkata Police claimed.
The mother is probably suffering from "postnatal depression" which led to the killing of her baby, the officer claimed.
On Sunday police started a probe after the mother alleged that her baby was kidnapped by an unidentified person from their residence.
She had alleged that an unknown man barged into her flat in the afternoon when she and the baby were alone at home. She was hit by the unknown youth who fled with her baby, the police said.
A search was launched and police started questioning the security guard of the flat, the babysitter and the mother.
"There were several discrepancies in the claims of the woman, the babys mother. We started questioning her which continued for several hours after which she admitted committing the crime... it seems she is under severe depression that led to this mishap. We have arrested her," the IPS officer said.