The Cape Verde Swamp Warbler (Acrocephalus brevipennis) is an Old World warbler in the genus Acrocephalus. It breeds only on Santiago in the Cape Verde Islands. It previously bred on Brava and San Nicolau.

This small passerine bird is a species found in well-vegetated valleys, avoiding drier areas. It nests in reedbeds, 2-3 eggs are laid in a suspended nest.

This is a medium_sized warbler, larger than the Reed Warbler. It resembles that bird in appearance, grey-brown above, greyish-white below, with no obvious markings.

The geographical isolation of the bird on the Cape Verde Islands prevents confusion with other similar species.

The song is a distinctive liquid bubbling, like a bulbul.