Ngunjiri is an environmental scientist with an interest in sustainability, climate change, energy systems (renewable energy), environmental impact assessment, and landscape restoration. Ngunjiri has twelve years of biological sciences laboratory experience. He has participated in various research as a laboratory technician. Besides his formal work, he participates in riparian land tree planting activities and instilling a learning culture among the youth. He has a BSc in Environmental Conservation and Natural Resource Management from the University of Nairobi, Diploma in Applied Biology and short courses in Human Rights and the Environment, International Environmental Law, Environmental Governance, International Framework on Environmental Impact Assessment, and Introductory Course to the Basel Convention on the Control of Transboundary Movements of Hazardous Wastes and their Disposal and Regional Instruments on Hazardous Wastes. Currently, Ngunjiri works at Kenyatta University. He is also a member of Nature Kenya (a Birdlife affiliate) and Warubanga Community Resource Centre.