Ecosystem-based Adaptation (EbA) is a nature-based solution to climate change adaptation. As it focuses on the conservation, restoration, and sustainable management of natural resources, the EbA project could contribute significantly to climate change mitigation as one of its co-benefits. Thus, quantification of CO2 emission reduction and sequestration is essential. The EbA II project, funded by the Global Environmental Facility (GEF) and implemented by the Ministry of Forests and Environment, Nepal, and the United Nations Environment Programme, has been implementing EbA measures in the three hill and mountain districts of Nepal: Dolakha, Salyan, and Achham. This chapter aims to quantify the CO2 sequestration and emission reduction resulting from the implementation of EbA measures in these districts. This findings demonstrates that the EbA II project contributes to reducing approximately 194,053 tons of CO2 annually, and within the project’s 5-year period, it contributes to lowering nearly one million tons of CO2. This paper provides evidence to position Ecosystem-Based Adaptation as a crucial approach to addressing climate change adaptation and mitigation. Therefore, the findings are vital for informing the government’s future climate change-related project design and implementation.