Background: Double-lumen catheter (DLC) remains an essential vascular access for many patients undergoing haemodialysis who lack a mature arteriovenous fistula or graft. Despite their clinical necessity, DLC use is associated with a high risk of preventable complications. Although infection-prevention guidelines emphasize aseptic technique and standardized catheter care, the ethical foundation underlying these practices, particularly the principle of non-maleficence, has not been clearly articulated within the context of DLC care. This study aims to analyse the concept of non-maleficence as applied to DLC care in haemodialysis nursing. Methods: A concept analysis was conducted using Walker and Avant’s methodological framework. Relevant nursing ethics and clinical literature published between 2016 and 2025 were systematically identified through PubMed, Scopus, ScienceDirect, and ProQuest. The analysis examined defining attributes, antecedents, consequences, and empirical referents, alongside the development of model, borderline, and contrary cases to illustrate clinical application. Results: Ten articles met the inclusion criteria. Non-maleficence in DLC care was characterized by three core attributes: evidence-based harm prevention through aseptic practice, continuous monitoring with timely response to emerging risks, and rational clinical decision-making regarding vascular access use. These attributes are shaped by nurses’ clinical competence, organizational support, and availability of resources and are reflected in outcomes including infection rates, catheter function, and avoidance of preventable harm. Conclusion: Non-maleficence in DLC care extends beyond an ethical principle and functions as a practice-based framework guiding harm prevention in haemodialysis settings. Clarifying this concept strengthens ethical clinical judgement and supports safer, more consistent nursing care.