The impact of natural hazards on buildings’ long-term environmental performance has gained the attention of the building industry as a result of the increasing environmental loss due to hazard events devastating the built environment around the world. This study explores the role of natural hazards in the perspective of building long-term environmental performance, as well as the environmental value of hazard mitigation. Accordingly, we propose an innovative Life Cycle Assessment (LCA) framework that can incorporate building damage due to hazards and converting this data into quantifiable environmental metrics. Moreover, by incorporating buildings’ environmental impacts attributable to hazards as derived from the LCA framework, we arrive at a Benefit-Cost Analysis (BCA) to justify the environmental desirability of hazard mitigation actions. Two case studies are presented: the first one assesses the environmental performance of a single reinforced concrete building under seismic risk; the second assesses the environmental justification for seismic retrofit on a region scale. The results show that, while the expected environmental loss caused by natural hazards is significant, such loss can be effectively reduced by pre-event mitigation; and that the benefits, in terms of reduction in environmental loss, outweigh the environmental impact of the mitigation itself. It is hoped that this study will serve as a basis for further research aimed at assessing the sustainability of constructed facilities facing natural hazards, and evaluating the environmental value of hazard-mitigation strategies.