Onontiyoh was a member of the Mohawk Nation of the Haudenosaunee Six Nations Confederacy. He is the first known indigenous person to graduate from the University at Buffalo. A member of the School of Medicine's Class of 1886, Onontiyoh graduated 18th out of 46 students. After graduation, Onontiyoh changed his name to Peter H. Onontiyoh and moved to Plainwell Michigan where he established a medical practice and lived for the rest of his life.
A photograph of Onontiyoh can be found in the National Anthropological Archives of the Smithsonian Institution and online in the ARTSTOR Digital Library.