The Hartland Shale of the Greenhorn Limestone is a geologic unit broadly distributed in north-central Kansas, that formed in the Western Interior Seaway, a Late Cretaceous epicontinental seaway in North America. Previously, the vertebrate fossil record of the Hartland Shale of Kansas was confined only to a tooth of the extinct lamniform shark Cretoxyrhina mantelli and skeletal remains of a plesiosaur, besides taxonomically uninformative bones and teeth of bony fishes. In this study, we describe 18 vertebrate taxa from the Hartland Shale in Republic County, Kansas, comprising five chondrichthyans (including C. mantelli), 12 osteichthyan fishes, and one reptilian taxon. These newly collected materials, which are dated approximately 93.95 million years ago around the Cenomanian-Turonian transition, provide new insights into the marine ecosystem and environmental conditions during the deposition of the Hartland Shale in Kansas.