Long-acting injectable depot buprenorphine is the latest opioid agonist therapy to be offered in Australia. There has been increasing scholarly interest in the lived experience of this treatment; however, the current qualitative research on this issue is limited to reports on the benefits and challenges individuals experience during treatment. This study expands and complicates this body of work by delving into the social, affective, and material aspects of the depot buprenorphine experience. By applying a Deleuzo-Guattarian framework to the analysis of 40 semistructured, open-ended interviews conducted with individuals who were either currently receiving depot buprenorphine, were in the process of discontinuing, or had discontinued treatment, we argue that depot buprenorphine is a technology of becoming situated within regimes of desire. That is, depot buprenorphine is a catalyst of social, affective, and material changes that is realized and dwells within a set of cocreated assemblages comprised of human and other-than-human actors. According to the regimes of desire at work within these assemblages, individuals in treatment pass through a series of thresholds that mark their becoming into different kinds of persons. Four critical thresholds emerged in participants’ reports of depot buprenorphine: thresholds of geography, freedom, the body, and abstinence. These thresholds opened up radical new ways of being for participants, with some being more positive than others. We close by discussing the implications our findings have for the ongoing delivery of opioid agonist therapies in Australia and elsewhere.