Professor Onyemah teaches Business Development, Professional Selling, Customer Relationship Marketing, Business-to-Business Marketing and Sales Force Management to undergraduate and graduate students. Prior to joining Babson College, he taught at Boston University and Lagos Business School. His industry and consulting experience includes work for the International Finance Corporation (IFC/World Bank), European Commission, Rumon Organization, SKG Pharma, Access Bank, Ecobank, Diamond Trust Bank, BCI, Rawbank, Avro Pharma, Sheraton-Ikeja Hotels, and Vivaldi Partners International. He has conducted missions in several countries including Benin Republic, Democratic Republic of Congo, Ivory Coast, Niger, Mozambique, Nigeria, Kenya, Uganda, Burundi, Tanzania, France, Spain, Italy, United Kingdom, and Mexico.

His principal area of research is Professional & Entrepreneurial Selling, Sales, and Sales Force Management. His articles have appeared in the Harvard Business Review, Journal of International Business Studies, Journal of Personal Selling & Sales Management, European Journal of Marketing, Journal of African Business, International Journal of Human Resources Management, and Marketing Letters. He has presented his works at several international conferences. Additionally, he has won a number of research and teaching awards including the M. Wayne DeLozier Best Conference Paper Award, Academy of Marketing Science 2006, American Marketing Association (AMA) Sales SIG Doctoral Dissertation Award 2005, and Boston University's Beckwith Award for Teaching Excellence and Service.