The family Nimravidae is a group of cat-like carnivorans that evolved sabertooth forms in parallel to Felidae. The last records of nimravids are represented by species of the North American genus Barbourofelis. Fossils of Barbourofelis found in Clarendonian North American Land Mammal Age (NALMA) deposits of California represent the western-most occurrences of the genus. Here we describe new material of Barbourofelis whitfordi from the late Miocene Dove Spring Formation (12.5–8 Ma) of the northwestern Mojave Desert, southern California, including the first known saber and confirmed upper cheek dentition of the species. Consistent with the delayed canine eruption observed in other Barbourofelis species, the newly discovered permanent cheek teeth are associated with deciduous upper canines. The upper and lower third premolars of B. whitfordi are larger in size relative to the carnassials, and less reduced in cusp morphology than other Barbourofelis species. In this regard, p3 morphology and size in B. whitfordi resemble that of the Eurasian Sansanosmilus more so than its congeneric species. The known stratigraphic range of B. whitfordi within the Dove Spring Formation spans a two-million-year period from 10.5 to 8.4 Ma. Based on a distal humerus described in this study, the record of Barbourofelis in the Dove Spring Formation now extends to the Cl1–Cl2 boundary at ∼12 Ma. A comparison of known Barbourofelis in the United States revealed that the B. morrisi—B. loveorum—B. fricki sequence might represent a single anagenetic lineage, whereas B. whitfordi represents a side lineage contemporaneous with B. morrisi during much of the Clarendonian NALMA.