A key concern of the global value chain (GVC) and global production network (GPN) literature relates to whether and how actors, especially in the Global South, upgrade by generating and capturing more value. To date, such research has predominantly focused on the economic and social aspects of upgrading. In this article, we leverage selected insights from economic geography to advance our understanding of the environmental dimensions of upgrading and downgrading in GVCs and GPNs. We develop an analytical framework that distinguishes the processes of environmental upgrading, in terms of value creation and appropriation, from the resultant outcomes (biophysical manifestations, impacts on market access, and reputation). Furthermore, the framework is considered from the upgrading perspectives of multiple actors instead of focusing only on lead firms and other powerful actors. We illustrate how to apply this framework through a case study of the Kenya–UK horticulture value chains. We show that despite the uptake of environmental upgrading practices, as required by UK supermarkets and transmitted by Kenyan export firms with the facilitation of government agencies, Kenyan farmers have mostly experienced environmental downgrading, with some negative effects also affecting farmers and other resource users beyond the value chain. [ABSTRACT FROM AUTHOR]