Vexillum caloxestum is a species of small sea snail, marine gastropod mollusk in the family Costellariidae, the ribbed miters.
The length of the shell attains 16 mm, its diameter 6 mm.
(Original description) The shell is obovate-fusiform. The pointed spire is turreted. The whorls are somewhat rounded above and sparingly plicate at the ribs. The interstices are pointed and striate. The colour of the shell is olive-green and lead. The body whorl is decorated with a narrow white band. The columella is four-plaited. The aperture is very dark within.
This marine species occurs off the Andaman Islands.