After years of research and theorisation connected to education for sustainable development, the holistic core of sustainability seems to have disappeared within the frames of the social, environmental and economic pillars. This article suggests a post-humanism inspired understanding of a sense of belonging. Even though the phenomenon of belonging is ascribed to social sustainability, the post-human theoretical toolkit challenges the humanism-based understanding of a sense of belonging as a human-related phenomenon. Using Deleuze and Guattari’s rhizome and affect concepts and Barad’s concept of intra-action, we show the connections between the human and nonhuman elements constituting each other in our world. We conclude with the implications that using post-human language (to understand belonging) may have for policy, Early Childhood Education and care (ECEC) practice and theory.