One Health discourse rightly stresses human–animal–environment interdependence, yet its normative footing can be thin and often defaults to strong anthropocentrism, valuing non-human beings and ecosystems only instrumentally. This perspective focuses on clinical decision-making and proposes a shift from strong anthropocentrism to weak anthropocentrism. weak anthropocentrism maintains the human-centered mandate that underpins medicine and public health while at the same time requiring proportionality, least harm, and intergenerational responsibility that acknowledge intrinsic—not merely instrumental—value in ecological systems and non-human life. Building on One Health's systems thinking, the framework offers a pragmatic approach rather than a radical turn to biocentrism or ecocentrism, and it recognizes ongoing debates about prudential versus radical interpretations within One Health. We illustrate feasibility with green oncology, where clinically equivalent options are selected to reduce life-cycle emissions, waste, and antimicrobial pressures—showing how ecological considerations can be integrated without compromising patient or population outcomes. The proposal aligns with contemporary regulatory strategies that recommend a One Health lens and invites a practical recalibration of public health policy: expand evaluative criteria, embed ecological reasoning in decision processes, and align clinical benefit with long-term planetary stewardship. Weak anthropocentrism thus offers a workable, ethically coherent route to extend “do no harm” beyond humans while remaining faithful to the core commitments of both clinical care and public health.