She has a BSc. (Hons) Food Technology and Nutrition and MSc, Food Technology from the University of Nairobi and PhD in Food Science and Postharvest Technology from Jomo Kenyatta University of Agriculture and Technology. Prof. Onyango has received postgraduate training in Advanced Food Technology from the Hebrew University of Jerusalem and also in Agricultural Research for Development from the International Centre for development-oriented Research in Agriculture, Wageningen, the Netherlands in 2002 and 2006 respectively.