Homo rudolfensis fossil remains have been found at Koobi Fora, Kenya, and appear very similar to Homo habilis, such as a bell shaped brain case, high forehead with no sulcus behind the reduced suprortibal torus, and reduced prognathism.

However, H. rudolfensis has a long face that is widest in the middle, a larger brain (751 cc), and presumably a larger body size. H. rudolfensis retains many features similar to Australopithecus including a shallow palate, prominent check bones, thick dental enamel, large cheek teeth, and post-orbital constriction of the braincase. Despite the large cheek teeth, prominent cheek bones and marked post-oribital constriction, H. rudolfensis lacks the robust cranial bones, megadotnia or strong muscle attachments, such as a sagittal crest, seen in Paranthopines.

To date, no crania have been definitely associated with post-cranial material, though this point continues to be debated regarding two large femurs. Some anthropologists argue the size differential between H. rudolfensis and H. habilis is a result of sexual dimorphism, and therefore H. rudolfensis are actually males of the species H. habilis. Others maintain that the features shared between the two species, are the same seen in all Homo and that the specimens are too distinct, and if true, then at least two distinct species of Homo lived contemporaneously in East Africa.

The type specimen for H. rudolfensis is the nearly complete cranium KNM-ER 1470 which was found at Koobi Fora in 1972 and dates to 1.8 – 1.9 million years ago.