This dissertation examines the role of informal sector in effective solid waste management in Nairobi County. It argues that the involvement of informal sector in solid waste management in Nairobi is critical in ensuring effective solid waste management. It proposes ways of mitigating the negative environmental impacts, promoting the practice of agricultural activities and entrepreneurship development as well as promotion of a healthy population. This happens if there is proper management of waste value chain, from generation, picking, and transportation to disposal using a multi-stakeholder approach. The study had three objectives: to assess the effect of involvement of informal sector in solid waste management in Nairobi, to identify the determinants of efficient solid waste management through informal sector, and to assess the willingness of formal sector in working with informal sector in solid waste management. The study used quantitative research and both descriptive and inferential research designs especially factor and regression analysis. Self-administered survey questionnaires were given to a sample of 300 respondents in the public sector, environmental groups, regulatory bodies, health practitioners, informal sector players in areas affected by solid waste menace, and entrepreneurs in informal settlements related to the solid waste chain. The study recommended that the government of Kenya at both National and County levels ought to have a paradigm shift in solid-waste management, by appreciating that solid waste management goes beyond solid waste disposal and encompasses the entire solid-waste value chain that starts from generation, picking, and transportation to disposal. The integrated approach to solid waste value chain enables the formal sector to incorporate the informal sector that plays a great role in this process. This helps in mitigating the negative environmental impacts, promotes the practice of agricultural activities, entrepreneurship development and the promotion of a healthy population.