Education systems globally are implementing competency-based education (CBE) reforms. Vietnam's leaders have also adopted CBE in a comprehensive reform of its education since the early 2010s. Although the global idea of CBE has been widely adopted and recontextualized in various educational contexts, implementing the reform at the local level (e.g., teachers in schools) is never a linear and simple process. Given the complicated sensemaking process of competency and competency teaching, this study explores how Vietnamese teachers made sense of key competencies and adapted their teaching to competency development. Informed by a sociocultural approach and the sensemaking perspective, this study draws from a dataset of 91 secondary teachers collected over three years (2017-2019), with a particular focus on longitudinal analysis of eight teachers. The findings shed light on teachers’ ambivalence as they made sense of the target competencies and aligned their practices with the new CBE reform. Based on their prior experiences and worldviews, teachers made sense of competencies as learning foundational knowledge and skills, in addition to developing good attitude, character, and morality. Over the years, they placed a stronger emphasis on the competencies’ process-orientation, integration, and real-life application toward whole-child development. Despite teacher sensemaking and changing practices, the performativity culture for high learning outcomes still prevailed, making teaching competencies for life a challenging task. Contributing to the CBE literature and practice, this study illustrates the long and complicated process through which teachers recontextualize the CBE pedagogy. It also suggests how teacher practices can be better supported to transition to the new CBE curriculum.