In this chapter we explore how Strategic Supplier Relationship Management (SSRM) can be a critical factor as part of the sustainability integration. Our case study is Sellafield Ltd. Sellafield is a highly complex and hazardous nuclear site managing more radioactive waste than any other nuclear facility in the world. A substantial volume of the waste is currently stored in the four legacy ponds and silos across the site. Due to the age and condition of these facilities, comprehensive programmes are underway to remove and transfer the waste to new facilities on the site that meet modern safety standards. Ensuring this work is done safely and securely is one of our top regulatory priorities. Removal of the waste inventory is expected to take many years to complete. Once the full waste inventory has been removed from the legacy ponds and silos they will be demolished. Considering the national and international interest of this organisation, we study their holistic supply chain management—highlighting their meticulous supplier selection, alongside collaborative strategies—and the stakeholders’ engagement approach, as part of their co-creation of meaningful and measurable initiatives, generating long last value for everyone involved. In this way, and both seizing opportunities and mitigating challenges, such as cultural resistance and regulatory hurdles, we can see and conclude that SSRM is a strategic enabler for sustainability transformation.