This theoretical commentary introduces the concept of connectivity justice and discusses how it can be utilized in research on mobile, digitally reliant lives. Connectivity justice reframes questions of mobility and data justice for a post-digital world in which digital connections have become both indispensable and intrusive. The concept extends recent work on digital disconnection by examining the institutional and sociotechnical drivers of connectivity (in)justice, such as state actors, tech industry, labor conditions, and cultural norms, rather than individual-level correlates alone. By combining the capabilities approach with a feminist ethics of care, connectivity justice highlights that justice today involves not only equitable access to infrastructures but also the relational capacity to connect well, to engage, withdraw, and sustain digital life responsibly. This lens opens new directions for mobilities research, and beyond, inviting analyses of how digital infrastructures, labor platforms, and everyday practices shape people's freedoms to move, communicate, and care. In doing so, it bridges normative and empirical inquiry, providing a vocabulary for understanding justice as an evolving balance between autonomy and interdependence within networked societies.