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

In sculpture the shell resembles Vexillum obeliscus, but straight and compressed at the sides, and slightly truncated above the contracted termination.

Sowerby II remarks that in sculpture this species resembles Vexillum obeliscus (Reeve, 1844).

To a certain extent there is some similarity; but the ribs in V. obeliscus are finer and more numerous, and the spiral sulci between them much deeper than in V. subtruncata.

The ribs, too, in the former are subgranulous at the points where the spiral lirae between the sulci come into contact with them, whilst in the latter they are smooth and regular.