<p>Wire Arc Additive Manufacturing (WAAM) is increasingly being explored as a viable alternative to conventional subtractive and powder-based manufacturing routes for the production of medium- to large-scale metallic components. This review critically examines recent Life Cycle Assessment (LCA) studies on WAAM with the aim of identifying the conditions, design strategies, and process configurations under which WAAM can offer environmental advantages. Following a systematic review, significant methodological inconsistencies across the literature are identified, particularly in terms of system boundaries, functional units, and impact indicator selection. These inconsistencies include the widespread reliance on aggregated endpoint indicators without corresponding Global Warming Potential (GWP) midpoint results, the use of hybrid or incomplete life cycle inventories, and a limited consideration of how process parameters influence both sustainability outcomes and component quality. Such heterogeneity affects the robustness, comparability, and generalisability of existing studies, limiting the reliability of cross-study assessments and potentially leading to inconsistent interpretations of WAAM environmental performance. Based on these findings, the need for more standardised and transparent assessment frameworks is emphasised, and directions for future research are proposed to improve methodological robustness and support more reliable environmental benchmarking of WAAM.</p>