Mutahi holds a Bachelor’s degree in Forestry from Moi University, obtained in 2004. In 2008, he joined Africa Harvest to work on the Tree for Energy project, which was funded by the Ministry of Energy, Kenya. Following the successful completion of the project and gaining experience in community-based initiatives, he continued working in the same region on a project funded by the Alliance for Green Revolution in Africa (AGRA). 

Additionally, he has been involved in various other projects, including an IFAD-funded initiative promoting an integrated farming system for sustainable livelihoods of smallholder farmers in Kisii and Nyamira counties. They also participated in a World Vision project funded by Bandaptai in Bomet County, which focused on developing a market system for poultry, sweet potatoes, and dairy products. Another project they were involved in was the InnoFoodAfrica project, funded by the European Union, which aimed to promote climate-resilient crops in Busia and Tharaka Nithi counties. Currently, he is participating in the RESAf project on land restoration, livelihoods, and carbon credit, funded by Climate Asset Management. This initiative operates in Kwale, Narok, Elgeyo Marakwet, and Kilifi counties.