He followed this with various roles in Micere Githae Mugo and Ngũgĩ wa Thiong'o’s Trial of Dedan Kimathi and Francis Imbuga’s Betrayal in the City which were also presented at All Africa Festival of Arts and Culture (FESTAC) in Nigeria in 1977.
It is said that Kenyan film experts recommended him at a very early stage for the role of Owour, in Nowhere in Africa, but he could not be found, having moved away from Nairobi to Kisumu, in the Western part of Kenya.
A local casting agent tracked him down to his home village near Lake Victoria and offered him the role that brought him fame at an international level.
[1] He has been in several major film productions, including Ivory Hunters (aka "The Last Elephant") (1990), Eyes of a Witness (1991), Nowhere in Africa (2003), King Solomon's Mines (2004), and The Constant Gardener (2005).
Onyulo fell sick while at his rural home at the foot of Kajulu hills and was rushed to a private hospital and died a week later.