While extant research suggests that holding biospheric values may foster environmentally friendly behavior, we need to learn more about the development of such values at an individual level. Our conceptual framework proposes that individual environmental identity could play a role in the formation of a biospheric value orientation. We conducted two cross-sectional surveys (N = 494, N = 107) and a quasi-experimental study (N = 271) in the US and Europe and with demographically different samples to investigate this conceptual linkage. Our findings show that stronger (vs. weaker) self-nature connections in individuals are related to stronger (vs. weaker) biospheric value orientations, which in turn are associated with various forms of sustainable behavior. Our research links two major literature streams in environmental psychology (i.e., research on self-nature connections and biospheric values) by proposing a developmental account of the relations between environmental identity and relevant values.