Three new species of Polychaeta (Annelida) are described from a benthic infaunal collection made in a seagrass bed dominated by Syringodium filiforme, manatee grass, at 8–9 m depth, in Bermuda: one species of Caulleriella (Cirratulidae), one of Schistomeringos (Dorvilleidae) and one of Exogone (subfamily Exogoninae, Syllidae). The syllid is briefly described here but not named because the only two specimens have been misplaced. The new cirratulid has a short prostomium with a novel arrangement of bifid hooks in both neuro- and notopodia, the new dorvilleid has furcate setae with subequal tynes in all setigers, and the new syllid has a novel arrangement of the simple setae. The polychaete diversity of Bermuda was considered to be relatively well studied, with a low diversity compared to similar subtropical locations and with a low degree of endemism compared to other oceanic islands. Identification of these three new species from the seagrass rhizosphere, in combination with recognition of other unidentified and misidentified species from the same collection, show instead that polychaete diversity in Bermuda is notably higher than recently reported and includes several species not reported from other geographic locations. Seagrass bed infaunal diversity is especially poorly documented.