Vexillum millecostatum is a species of small sea snail, marine gastropod mollusk in the family Costellariidae, the ribbed miters.

The solid, elongate shell has an oblong-fusiform shape.

It is closely, finely longitudinally ribbed, with impressed revolving striae at the base.

It is orange yellow to dark chestnut-brown, sometimes with two interrupted lighter bands.

[2] [3] This species occurs in the Eastern Indian Ocean and western and central Pacific Ocean; also off Papua New Guinea and Australia (Queensland.)