The polychaete annelid Kingnites diamondi, a new paulinitid genus and species, is described from the Silurian of Baltoscandia. Its large maxillae differ morphologically from those of all other known paulinitids, particularly in being very elongate and having conspicuous myocoele openings and posterior portions of the first maxillae (MI). Albeit rare, this polychaete taxon is highly characteristic and appears to be confined to the Wenlock–Ludlow transitional interval on Gotland, Sweden, and ranges into the upper Ludlow on Saaremaa, Estonia. All samples yielding this species derive from strata formed in proximal carbonate platform environments. The temporal and geographical distribution indicates that it first appeared in Gotland and subsequently spread north-eastwards to the present-day Saaremaa. Kingnites diamondi adds to the list of known members of the Paulinitidae and reinforces the importance of this family, in terms of abundance and diversity, in Silurian polychaete faunas of Baltica. This is the biggest paulinitid recorded from the Silurian with an inferred body length of approximately half a metre and its diagnostic jaws may serve as a proxy for shallow water, backreef (marginal marine to lagoonal) environments