Today’s world is characterised by new levels of complexity; however our societies remain deeply embedded in and dependent on a functioning biosphere. A biosphere that is increasingly being degraded by human activities. In this complex and intertwined world, acute shocks as well as chronic pressures of unsustainable activities have therefore become a prevalent feature. Together these shocks and chronic pressures create a complex risk landscape that we need to navigate with inter- and transdisciplinary solutions. However, the study of risk and the risk assessment tools in use, are siloed into scholarly disciplines and mismatched with the complexity at hand. In this thesis I tackle this mismatch, by using a social-ecological systems perspective and a variety of methodological approaches. Together the four papers of the thesis develop the interdisciplinary concept of sustainability risk and start to operationalise it through the application to national food systems and corporate sustainability risk assessment. Paper I introduces the concept of sustainability risk that I use and develop through-out the thesis. The paper also summarises some of the key definitions of risk within different disciplines and proposes five key dimensions that need to be adapted and developed in order for the existing risk assessment methods to fully capture risks in a complex world. Papers II-IV all represent applications of the concept of sustainability risk to different contexts. Paper II addresses national food supply risks and highlights how diverse risks to national self-sufficiency can come from low self-sufficiency (resulting in risk from trade disruptions) and low production diversity (resulting in risk from production shocks). Paper III addresses the data limitations we encounter when attempting to assess corporate sustainability risk and aims to overcome some of these limitations by developing fifteen novel reporting variables. These variables also contribute to the ongoing efforts to standardise corporate sustainability reporting. Paper IV builds on Paper III and develops an initial framework for assessing the risks to long-term natural resource production emanating from the impacts of corporate activities, thus broadening the conceptualisation of what risk is and how we assess it in the corporate sphere.