The Cretaceous witnessed a radiation of rove beetles (Staphylinidae), the most species-rich beetle family. Although most staphylinid subfamilies have been documented from Cretaceous strata over the world, there has been no fossil record of the subfamily Pseudopsinae until a recently reported fossil from the 99-Ma-old Myanmar amber. Here we describe a new compression fossil from the Lower Cretaceous Yixian Formation of northeastern China. It is described as Cretaceonanobius fossilis. gen. et sp. nov. and assigned to the extant subfamily Pseudopsinae, based on the well-preserved carinae on the pronotum, a carina on ventrites II and III, and distinctly separated mesocoxae. The discovery of Cretaceonanobius fossilis gen. et sp. nov. backdates the earliest fossils record of Pseudopsinae to 125 Ma in the Northern Hemisphere and sheds new lights on the evolution history and paleobiogeography of this subfamily.