This study examines the current capacity, challenges, and training needs of agricultural extension staff in the northern mountainous region of Vietnam in the context of climate change. Conducted between 2021 and 2022, the study employed a cross-sectional survey design using stratified sampling, covering 151 respondents, including both extension workers and leaders, from Thai Nguyen and Bac Kan provinces. Semi-structured questionnaires combining multiple choice, Likert scales, and open-ended questions were used to gather data. The findings reveal that while most extension staff possess tertiary education, they have limited practical experience and technical training in climate change adaptation. Female staff dominated the workforce, and many staff were required to work across multiple technical domains beyond their academic training. Key challenges include a lack of access to climate-smart agriculture training materials, inadequate models for demonstration, and limited capacity to advise on climate-induced risks such as pest outbreaks or cropping calendar shifts. Training needs were prioritised in climate-resilient technologies, communication skills, and participatory planning. Preferred learning methods included on-farm demonstrations and study visits, with lower preference for online or self-guided learning. The study highlights the urgent need for targeted, gender-responsive, and practical capacity-building interventions to enhance extension networks’ ability to support smallholder adaptation in vulnerable regions.