Our aim was to estimate the prevalence of HCV in a highly vulnerable population of substance users living with social difficulties and marginality who came into contact with the mobile harm reduction service in the city of Bologna (Northern Italy). Testing was offered in a van (mobile unit) by using a point-of-care HCV antibody test. For the HCV RNA test, the Xpert HCV Viral Load Fingerstick Test was used. Participants with a detectable HCV RNA were accompanied within two weeks to the Infectious Diseases Department Sant' Orsola Hospital Bologna to start HCV treatment. With regard to the main study findings, 54% reported having never been HCV tested before; a prevalence of HCV RNA of 6% among all participants and 22% among those injecting drugs was found; among the HCV RNA positive participants, 80% were accompanied to treatment. Our study suggests that mobile harm reduction services, in networks with healthcare facilities, are able to offer a continuous HCV screening service and linkage to care for people with drug use living in socially marginalized conditions.