Many of the dead included trapped workers who jumped from the smouldering building engulfed by flames, witnesses at the scene said. At least 25 people died and many more were hurt.
Fire official Golam Mostafa said the fire started in a ten-storey factory owned by local business giant Ha-Meem Group in the Ashulia industrial zone, just outside the Bangladeshi capital, Dhaka. The government has ordered an investigation into the causes of the blaze.
Interior minister Shahara Khatun visited the site, and said her ministry would investigate whether the fire was related to recent violent protests at textile factories over wages.
Monir Hossain, a local journalist at the scene, said the blaze broke out on the two upper floors during a lunch break. A gate on a stairwell was locked, trapping people inside the factory, which mainly produces T-shirts for international brands.
Officials predicted the death toll would rise, said Islam.
A witness named Kader said he saw 50 to 60 people jumping off the tenth floor to escape the raging blaze.
About 13,000 people work at the factory on shifts each day, though most were outside buying lunch when the fire started, it was reported.
Soldiers and police cordoned off the building as firefighters continued their search as the fire was brought under control.
The company and the Bangladesh Garment Manufacturers and Exporters Association said they would give 100,000 takas (about 895) compensation to the families of the dead and pay for the treatment of the injured.