Understanding that sustainability transitions (ST) are embedded in global networks of capitalist production, this paper proposes a research agenda using the Global Production Networks (GPN) to explain the relational geographies of sustainability transitions. A cross-fertilisation between GPN and ST literature allows understanding the relationships between diverse actors influencing or affected by global production systems with ongoing (or requiring) sustainability transitions. Moreover, it emphasises on the iteration between space, socio-technical systems and regimes. The contributions of a GPN approach are, first, its attention to actors to explain enablers and obstacles for change. Second, its attention to power relations between firms and non-firm actors influencing the directionality of change. Third, its focus on processes of upgrading and strategic coupling to explain spatial implications. Fourth, its critical approximation to explain different outcomes in different regions (often found as the dark side of GPN).