In response to the growing impacts of climate change, Climate-Smart Agriculture (CSA) offers an integrated approach to enhance productivity, resilience, and emission reduction. This study promotes CSA adoption among smallholder farmers in northern Vietnam’s mountainous region by documenting the implementation and early outcomes of a community-based CSA initiative and drawing lessons for future scaling. The project combined farmer training with technical and material support to apply CSA practices such as organic composting, efficient irrigation, agroforestry-based home gardening, intercropping, fruit tree cultivation, and biological pest management. Using a mixed-methods design, data was collected through preliminary surveys, citizen science–based monitoring via the ESRI Survey123 platform and follow-up interviews assessing changes in food security, income, labour and environmental conditions. Findings indicate that diversified home gardens integrating fruit trees, organic vegetables and composting improved household food security, diversified diets and increased income by 10%, while reducing women’s labour burden related to irrigation and forest gathering. The project also fostered stronger social cooperation, peer learning and a shift toward sustainable, market-oriented production systems. Overall, the study provides practical evidence to inform policies supporting farmer-led and community-based CSA initiatives, emphasising the importance of continuous capacity building, local market development and institutional support to scale climate-resilient agriculture across upland regions.