Global ethics in recent scholarship has been understood in largely substantive terms as constituting a normative set of political principles, cultural values and religious moral imperatives. It has thus been commonly understood as a type of strong moral universalism with prescriptive moral frameworks rooted in foundational principles. In contrast, this thesis understands a global ethics in sociocognitive terms in ways of thinking, feeling and acting; it is found in a moral consciousness of the need for an ethics on a planetary scale which is articulated in emotional responses to global issues within critical publics throughout the world and embodied in ethico-political practices that shape common struggles around a global justice politics that extends beyond national frames of reference. By this understanding, its conceptual indicators can be seen in discourses of co-responsibility emerging around perceived global threats that can generate social bonds in transnational solidarities and collective-identities. Understood through the normative perspective of critical cosmopolitanism, this study examines a global ethics—as emerging out of a critical way of seeing the world, in moral evaluations and critical diagnoses of social conditions—articulated in cross-national political projects which are digitally mediated in social media networks. There has been scarce scholarship on the relationship between digital technology and a global ethics—a gap this thesis fills by focusing on the way in which global ethics today arises within interactive, creative and collaborative digital spaces built across social media networks. Despite its imbrication in new digital systems of exploitation, domination and surveillance capitalism, the central argument of this thesis is that social media networks open digital spaces integral to expressions of a post-traditional ethics today: as a new global communications ecology, they have (a) heightened our sense of moralpractical reflection toward the non-human world and the universe of distant others and (b) offered digital symbolic spaces within which to build collective action frames in response to global risk through building shared antagonisms, common meanings and radical imaginaries of alternative futures which can mobilise collective actions, in multiple urban spaces, across the globe. To support this central argument, the thesis draws on the recent cross-national cases of digital activism in response to global problems in the form of the Occupy Everywhere, Friday- For-Futures and Global Frackdown movements. These movements exhibited network practices that displayed social, symbolic and cognitive articulations of a cosmopolitan citizenship.