Relational values feature prominently in recent international efforts to protect global biodiversity. In this article, we provide a conceptual approach for researchers, facilitators and policy-makers to adequately represent place-based relational values in assessments of nature's value that inform practice and policy. We suggest employing horizontal portability as an alternative and complement to the dominant mode of assessing nature's value via vertical subsumption. Vertical subsumption is a process through which particular values are generalised into overarching categories to conform to more general value concepts and thereby stripped of their place-specific meanings. In contrast, horizontal portability is introduced here as a conceptual approach that maintains the contextual rootedness of place-based local expressions of value while also communicating them across places, knowledge systems, and communities. The movement (i.e. ‘porting’) is ‘horizontal’ because it allows relational values rooted in a particular biocultural context to speak to different contexts on equal terms. We discuss how research on the value of nature and people –nature relationships can support horizontal portability. Finally, we provide recommendations for the application of horizontal portability that promotes more plurality and greater inclusion of place-based relational values in research, policy and action. Read the free Plain Language Summary for this article on the Journal blog.