The pervasive influence of communication technology has profoundly shaped contemporary life, significantly impacting global education. The COVID-19 pandemic accelerated the adoption of technologies like social media platforms and massive open online courses (MOOCs) as substitutes for traditional in-person education, exposing shortcomings, particularly in regions with limited online infrastructure. Although extensive research exists on online education, including blended learning models, the challenges associated with their effective implementation remain underexplored. This study aims to address these gaps by examining the adoption of blended learning within Vietnamese universities during the pandemic through the lens of Activity Theory. This framework, which analyzes the dynamic interactions between individuals, tools, and their sociocultural environment, provides a deeper understanding of how students, educators, and institutions navigate blended learning. This study employed semi-structured interviews with administrators, lecturers, curriculum developers, and students across four campuses of a university in Vietnam. The findings highlight key challenges related to student engagement, academic dishonesty, and constraints in institutional infrastructure, underscoring the need for targeted strategies to enhance blended learning outcomes.