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

[1] The seaweed is olive green at the base becoming a darker green distally.

The thallus spreads outward to about 18 centimetres (7.1 in).

[1] The species is found around much of Asia and the Pacific Islands as well as Australia and New Zealand.

[2] In Western Australia, it is found along the coast in a large area extending from around the Kimberley, south as far as Esperance in the Goldfields-Esperance region of Western Australia.