The mammalian hyoid plays an integral role in swallowing, respiration and vocalization. Anthropoid primates have broad, cup-shaped basihyals suspended from the basicranium by soft tissues only. This configuration differs from most placental mammals, which have a rod-shaped basihyal connected to the basicranium via both soft tissues and a mobile bony chain called the anterior cornu. To better understand how the unique anthropoid hyoid morphology evolved, we use linear morphometrics to quantify hyoid morphology in 35 primates and outgroup species. We show that dermopterans have variable loss of cornu elements. Tupaia and all lemuroids except Daubentonia have a fully ossified anterior cornu connecting a rod-shaped basihyal to the basicranium, an ancestral pattern of mammals. Haplorhines collectively have reduced anterior cornu, and further changes in basihyal aspect ratio and volume occur within anthropoids. Lorisoid strepsirrhines independently evolved reduced anterior cornu and broader basihyals similar to tarsiers. Primate hyoids follow a different allometric scaling pattern from other mammals, consistent with the scaling of larynx from previous studies. Among primates, anthropoids tend to have larger hyoids than allometry predicts, but strepsirrhines have smaller hyoids than expected. We hypothesize that anthropoids’ enlarged ventral hyoids can support larynxes with hypertrophied air sacs. Their reduced anterior cornu may facilitate vocal tract lengthening to lower formant frequency spacing and exaggerate body size cues in vocalization. Anterior cornu reduction in anthropoids is also a prerequisite for the descent of larynx among modern humans. Our results highlight several novel evolutionary patterns of hyoids in primates.