At FPT Shop, the 128-GB version has been topping sales for months, beating out the iPhone 11 and cheaper Android devices like the Samsung Galaxy A12 and A22.
CellphoneS and Minh Tuan Mobile reported similar results.
At The Gioi Di Dong, no Apple device made it to the top 10 list in terms of number of units sold, but iPhone 13 Pro Max (128 GB and 256 GB version) topped in revenues due to their high price tags.
"Despite having the highest price, the 13 Pro Max beat other Apple smartphones in sales," Nguyen Lac Huy, media representative of Cellphone S, said. "It was followed by the iPhone 11 after its price drop in late June."
The iPhone 13 Pro Max was launched last September, and pre-orders for it accounted for 70 percent of all Apple sales then. It also dominated the high-end smartphone segment (prices of VND20 million ($857) and higher).
Its closest competitor was the iPhone 11, which had a price tag of VND10.5 million.
Retailers expect sales of the 13 Pro Max to keep rising thanks to the price adjustment at the end of June, which brought it down to VND27 million.
"Buying the most high-end model is common among Vietnamese," Nguyen Huu Phuc, head of sales at Minh Tuan Mobile, said.
"Meanwhile, retailers also offered various promotions on the device, and so the iPhone 13 Pro Max always accounted for a large proportion of sales."
Huy of CellphoneS said the iPhone 13 Pro Max "will definitely retain its best-selling position" until new products are launched.