Marginella orstomi is a species of colorful small sea snail, a marine gastropod mollusk in the family Marginellidae.

The holotype of Marginella orstomi was collected at a depth of between 200 and 250 m, off Pointe Noire, Republic of Congo.

The shell has a ground coloration of dirty yellow with dark areas, and a pattern consisting of many dark grey transverse irregular zigzag lines sometimes crossed by spiral rows of small dots.

The color pattern on the outside of the body whorl is visible on the inside of the aperture, and the outer lip is thickened and deflected outward.

Both species are characterized by the presence of a white tooth on the inside of the outer lip near the posterior end.