Consistent with its liberal origins, the field of transitional justice is overwhelmingly concerned with harms done to human victims. Posthumanism, however, challenges the framing of humans as bounded and autonomous individuals, emphasizing that all of us are entangled within wider relational assemblages that reflect the deep interconnections between human and more-than-human worlds. The core aim of this interdisciplinary article is to demonstrate what posthumanism can potentially contribute to transitional justice in the sense of pluralizing how we think, ontologically and epistemologically, about it – and in particular about the concepts of harm and, relatedly, agency. In discussing how posthumanist ideas and concerns might be practically incorporated into the field, the article explores the utility of two key concepts – social-ecological systems and visceral geography.