He breathed his last at city’s Green Life Hospital around 10:45pm on Friday while undergoing treatment, BNP organising secretary Shama Obaid told UNB on Saturday.
She said Gias was admitted to the hospital a few days back with fever and diabetic problems.
The BNP leader left behind one son, two daughters and a host of relatives and well-wishers to mourn his death.
He was buried at Taj Mahal Road graveyard in the capital’s Mohammadpur area following a namaz-e-janaza at a mosque after Zohr prayers, Shama said.
Giasuddin was former state minister for relief and rehabilitation and the president of KM Obaidur Rahman Smriti Sangsad.
BNP acting chairman Tanique Rahman and secretary general Mirza Fakhrul Islam Alamgir expressed deep shock at his death.
In separate condolence messages, they prayed for salvation of the departed soul and conveyed their sympathy to the bereaved family members.