This article introduces the notion of sustainability objects as a label for objects that come with a claim of promoting a more sustainable mode of living. The purpose is to show that organizations that develop such objects construct a performative definition of sustainability. A case study of the development of a facility for the pre-treatment of food-waste-based biogas and biofertilizers serves as an empirical example of the development of sustainability objects. The analysis demonstrates that this development and concomitant defining of sustainability have involved the contextualizing of biogas and biofertilizers, entangling them in nets of relationships and endowing them with an agency of their own. With sustainability objects embodying definitions of sustainability, their success or failure as objects derive from the success or failure of the performative definitions that they embody, and vice versa. Asking why sustainability objects gain or lose ground is therefore suggested as a way of understanding the character and evolution of sustainability transition.