Disengagement from care among people with HIV (PWH) and hepatitis C (HCV) increases the risks of adverse health outcomes and poses significant barriers to achieving global HIV and HCV elimination goals. In accordance with the Joanna Briggs Institute framework, a scoping review was conducted to synthesize and highlight existing gaps in the literature on (dis)engagement in care among PWH and HCV. We searched for original studies on (dis)engagement in care among PWH and HCV in high-income countries using eight electronic databases from inception to May 2023. Our search yielded 4462 non-duplicated records, which were scoped to 27 studies. Definitions of (dis)engagement in care were diverse, with considerable heterogeneity in how retention was operationalized and temporally measured. Studies identified predictors of (dis)engagement to be related to drug and substance use (n = 5 articles), clinical factors (n = 5), social and welfare (n = 4), and demographic characteristics (n = 2). When engagement in care was treated as an exposure, it was associated with HCV treatment initiation (n = 3), achieving sustained virological response (n = 2), and maintaining HIV viral suppression (n = 1). Interventions to improve care engagement among PWH and HCV were limited to five studies using cash incentives (n = 1) and individual case management (n = 4). (Dis)engagement in care is a dynamic process influenced by shifting priorities that may 'tip the balance' towards or away from regularly interacting with healthcare professionals. However, inconsistent definitions render cross-study comparisons and meta-analyses virtually impossible. Further research needs to establish a standardized definition to identify patients at high risk of disengagement and develop interventions that leverage the nested HIV/HCV care cascades to retain and recover patients lost from care.