The fire broke out in the three-storey mosque at Ikhrajpora locality of Jawahar Nagar yesterday, trapping the watchman Alam Din Chohan of Lolab area of Kupwara, a police spokesman said.
He said Chohan died of asphyxiation and his charred body was later recovered.
The mosque was completely damaged in the fire, the spokesman said, adding that short-circuit was believed to be the cause of the fire.
The body of the deceased was handed over to his family members for last rites, he said.