Sustainable digital finance promises to enhance social and environmental outcomes by leveraging digital technologies. Yet, this promise is complicated by the rebound effect: the phenomenon where efficiency gains from innovation lead to increased consumption, thereby offsetting environmental benefits. This chapter explores the tension between digital financial inclusion and environmental impact, illustrating how technologies such as cloud computing and digital banking services, while ostensibly greener and more efficient, often spur behavioral changes that dilute their sustainability gains. Drawing on historical examples and extending the analysis to modern financial systems, the author argues that the rebound effect is not only likely but potentially desirable in the context of finance—where increased access and inclusion may justify higher resource use. The analysis challenges the notion of “sustainable” digital finance as an unqualified good and invites a more nuanced assessment of when and how rebound effects can be socially beneficial, particularly when they contribute meaningfully to poverty reduction and welfare enhancement.