Caulerpa subserrata is a species of seaweed in the Caulerpaceae family.

The seaweed has erect fronds that arise from repeating, cylindrically shaped, branching, glabrous surculus and often two or three individuals are found together.

The fronds are truncato-obtuse at apex and oval at the base tapering to a very short cylindrical stipe.

[1] The species was first formally described by the botanist Kintarô Okamura in 1897 as part of the work On the algae from Ogasawara-jima (Bonin Islands) as published in the Botanical Magazine, Tokyo.

[2] It is found along the coast of the Bonin Islands about 500 kilometres (311 mi) south of Japan.