The epidemiology of hepatitis C in Cambodia is not well-known. We evaluated the prevalence of hepatitis C virus (HCV) and risk factors in the HIV cohort of Sihanouk Hospital Center of Hope in Phnom Penh to strengthen the evidence for suitable HCV testing strategies among people living with HIV (PLWH) in Cambodia. All consenting adult PLWH without a history of HCV treatment were tested for HCV between November 2014 and May 2016 according to the CDC algorithm (HCV antibody II electro-chemiluminescence immunoassay, followed by COBAS® AmpliPrep/COBAS® TaqMan® HCV PCR and INNO-LIA® HCV Score immunoblot end-testing). Genotyping was performed using the line probe assay Versant HCV genotype 2.0®. The study enrolled a total of 3045 patients (43% males, median age: 42.5 years, <1% high-risk). HCV antibodies were detected in 230 (7.6%; 95% confidence interval [CI] 6.6–8.5). Upon further testing, HCV antibodies were confirmed in 157 (5.2%; 95% CI 4.4–6.0) and active HCV in 106 (3.5%; 95% CI 2.8–4.2). Viremic prevalence peaked among men aged 50–55 years (7.3%) and women aged >55 years (11.2%). Genotype 1b (45%) and 6 (41%) were predominant. Coinfected patients had a higher aspartate-to-platelet ratio index, lower platelets, a lower HBsAg positivity rate and more frequent diabetes. Based on logistic regression, blood transfusion antecedents (adjusted odds ratio 2.9; 95% CI 1.7–4.9), unsafe medical injections (2.0; 1.3–3.2), and partner (3.4; 1.5–7.6) or household member (2.4; 1.3–3.2) with liver disease were independently associated with HCV in women. However, having a tattoo/scarification (1.9; 1.1–3.4) and household member (3.1; 1.3–7.3) with liver disease were associated with HCV in men. Thus, our study found intermediate endemicity of active hepatitis C in a large Cambodian HIV cohort and provides initial arguments for targeted HCV screening (>50 years, partner/household member with liver disease, diabetes, increased aspartate-to-platelet ratio index) as efficient way forward.