As digital technologies increasingly shape children’s learning, development, and socialization, concerns over digital inequality have become more prominent, particularly in contexts with pronounced structural disparities. Guided by the Capability Approach, this study examines the relationships among digital inequality, digital exclusion, and children’s cognitive and emotional well-being. A two-wave longitudinal survey was conducted with 759 children to explore these dynamics. The findings revealed that digital skills, rather than access or outcomes, significantly predict digital exclusion, which mediates the association between digital skills and children’s well-being. Moreover, left-behind status moderates these effects, with left-behind children experiencing stronger negative impacts of digital exclusion on cognitive well-being. The results highlight the need for targeted interventions to address digital disparities, particularly for vulnerable populations. These findings contribute to the growing literature on digital inequality and provide actionable insights for policy and educational initiatives aimed at fostering digital inclusion. These findings also underline the critical role of social work interventions in mitigating the adverse effects of digital exclusion by fostering digital literacy, enhancing access, and addressing the unique needs of left-behind children.