Firefighters battled for hours to extinguish the blaze that started on the third floor and spread to the floor above, trapping call center employees.
Their chances of survival were “zero”, Davao’s Vice-Mayor Paolo Duterte said.
President Rodrigo Duterte, the vice-mayor’s father, visited the scene.
President Duterte, a Davao native, met families of the missing outside the burning NCCC mall.
The cause of the fire, which began on Saturday morning, is being investigated.
The mall’s marketing manager, Janna Abdullah Mutalib, said the blaze started on the third floor, where clothes, appliances and furniture were sold, the Philippines Star website reports.
Davao lies about 800km (500 miles) south-east of the capital Manila.
The fire comes as the country is coming to terms with a deadly tropical storm.