<p>Study throughput.</p>

Hepatitis C virus (HCV) infection remains a major public health challenge, with significant gaps in diagnosis and treatment in resource-limited settings. Hepatitis C self-testing (HCVST) offers a potential strategy to expand access, particularly in HIV clinical settings. We evaluated feasibility and acceptability of HCVST among high-risk populations in Nasarawa State, Nigeria when provided at antiretroviral (ART) clinics and one-stop shops (OSS) serving key populations (KP). 2,000 participants were enrolled between May 2023 and December 2023. Participants tested with either finger-prick blood-based or oral fluid antibody HCVST, and with or without health worker support. Follow-up documented results and linkage to qualitative RNA PCR confirmatory testing and treatment. Case-complete feasibility analyses were conducted across the HCV care cascade using chi-square tests (N = 1995). Acceptability was evaluated using a post-test survey score derived through case-complete factor analysis (N = 1868); associations between lowest decile acceptability score and participant characteristics were explored through regression analyses. Outcomes were compared by facility type (ART clinic vs. OSS). Free-text responses were thematically analyzed to contextualize findings. HCVST was feasible and acceptable. Of 226 reactive HCVST results (11.3%), 99.1% received RNA PCR testing. Among those with detectable RNA, 92% initiated treatment and 97% completed therapy. However, differences were observed by facility type. Participants in ART clinics were older, more likely to be female, and showed higher reactivity (15% vs. 8%) and treatment uptake (96% vs. 83%) than OSS clients. Acceptability was higher in ART clinics than OSS. HCVST was both feasible and acceptable in Nasarawa State, with some observed variations by facility type. These findings suggest that with differentiated service delivery models and adequate support for linkage, HCVST can increase HCV diagnosis, linkage to care, and treatment among high-risk groups in Nigeria, supporting integration of HCVST into national viral hepatitis elimination strategies.