Recent evidence indicates that the emergence of stone tool technology occurred before the appearance of the genus Homo1 and may potentially be traced back deep into the primate evolutionary line2. Conversely, osseous technologies are apparently exclusive of later hominins from approximately 2 million years ago (Ma)3,4, whereas the earliest systematic production of bone tools is currently restricted to European Acheulean sites 400–250 thousand years ago5,6. Here we document an assemblage of bone tools shaped by knapping found within a single stratigraphic horizon at Olduvai Gorge dated to 1.5 Ma. Large mammal limb bone fragments, mostly from hippopotamus and elephant, were shaped to produce various tools, including massive elongated implements. Before our discovery, bone artefact production in pre-Middle Stone Age African contexts was widely considered as episodic, expedient and unrepresentative of early Homo toolkits. However, our results demonstrate that at the transition between the Oldowan and the early Acheulean, East African hominins developed an original cultural innovation that entailed a transfer and adaptation of knapping skills from stone to bone. By producing technologically and morphologically standardized bone tools, early Acheulean toolmakers unravelled technological repertoires that were previously thought to have appeared routinely more than 1 million years later. Bone tools shaped by knapping found within Olduvai Gorge in Tanzania precede any other evidence of systematic bone tool production by more than 1 million years.