A widespread conversation has emerged around the concept of sustainability in management theory and practice today. The origins of this notion have forwarded a vision of economic development for improving social conditions in different parts of the world, as well as promoting environmental protection to reduce the harmful effects of economic activity on Earth (Brundtland Report, 1987). Emerging from these origins, solving sustainability problems today has come to signify attending to three seemingly distinct pillars: social equity, environmental protection, and economic development. In this dissertation I join these conversations by following recent theoretical discussions suggesting the pillars are actually interrelated instead of distinct. Specifically, I argue that to fulfill these aims an ontological shift is needed in re-conceptualizing sustainability as a process unfolding in practices of human and nonhuman constituencies. The dissertation comprises two papers, developing these theoretical arguments and demonstrating their empirical and applied value via two case studies. Marking the current moment as the Anthropocene, the first paper draws from research that challenges the centrality of humankind in management and organization studies, and problematizes the premises underlying the three pillars of sustainability. Informed by emerging ecological arguments in feminist thought, this paper develops becoming naturecultural as a novel conceptual frame for thinking current sustainability practices in organizations. The analytical workings of this frame are illustrated through a case study of an organic cotton supply chain. The second paper locates sustainability within a case study of a market-based fashion company, undertaking a strategic change to transform its operations. Bringing together the intellectual resources from Strategy-as-Practice and Corporate Sustainability literatures, I articulate the notion of intentional engaging as a conceptual tool to help unpack how sustainability, as processes and practices, is done in this organization. I develop a process framework, corporate sustainability as practice, from analyses of the case study, and advance corporate sustainability as a strategy-making process for addressing social injustice and environmental degradation perpetuated by production and consumption activities. Altogether, with these papers, the dissertation forwards two re-conceptualizations of sustainability from process ontology. These re-conceptualizations facilitate moving beyond human-centered approaches and toward performing more-than-human management and organization studies.