The incident took place in north-east Delhi's Karawal Nagar where the woman, Pooja, lived with her husband Vipin Kumar (28), their one-year-old son and in-laws police said.
The couple got married in April 2012.
"Around 11 PM yesterday, Pooja's in-laws informed her sister Madhu that she has committed suicide by hanging herself from the ceiling fan. However, Madhu reached the spot to find Pooja's body lying on the floor. She then made a PCR call," said a police official.
Police said as the couple was married for less than seven years, an SDM inquest has been initiated in the case under Section 176 of the CrPC.