The deceased was identified as Srabonti, daughter of Md Sohag of Bagherpara Upazila in Jeshore.
Dr Shoilendra Biswas, resident medical officer of KMCH, said Srabonti was admitted to the hospital on August 31 with dengue fever.
She breathed her last at 3:20 pm while undergoing treatment at Intensive Care Unit of the hospital.
So far, nine people died of the mosquito-borne disease in Khulna after the recent outbreak.
Meanwhile, the Directorate General of Health Service (DGHS) said a total of 788 dengue patients were hospitalised across the country in 24 hours till Thursday morning, showing 4 percent decrease in fresh dengue infection rate.
According to DGHS, 331 dengue patients were admitted to different hospitals in the capital while 591 dengue-infected people got released from city hospitals in previous 24 hours.
Besides, 457 dengue patients were hospitalized in different districts while 414 people were released from different hospitals across the country.
So far, 57 people died of dengue across the country, it said.
Currently, 3,371 dengue-infected people are undergoing treatment at different hospitals in the country. Of them, 1,729 are being treated at different hospitals in the capital while 1,642 at different hospitals outside Dhaka.