Objectives: There is limited research on health-related quality of life (HRQoL) among people who inject drugs (PWID). We evaluated the HRQoL and associated factors among a cohort of PWID in Australia. Methods: Participants were enrolled in an observational cohort study (the Enhancing Treatment of Hepatitis C in Opioid Substitution Settings Engage Study) from May 2018 to September 2019 (wave 1) and November 2019 to June 2021 (wave 2). Participants completed the EQ-5D-5L survey at enrolment. Two-part models were used to assess the association of clinical and socioeconomic characteristics with EQ-5D-5L scores. Results: Among 2395 participants (median age, 43 years; 66% male), 65% reported injecting drug use in the past month, 20% had current hepatitis C virus (HCV) infection, and 68% had no/mild liver fibrosis (F0/F1). Overall, the mean EQ-5D-5L and EQ-visual analog scale scores were 0.78 and 57, respectively. In adjusted analysis, factors associated with significantly lower EQ-5D-5L scores include older ages, female (marginal effect = −0.03, P =.014), being homeless (marginal effect = −0.04, P =.040), and polysubstance use (marginal effect = −0.05, P <.001). Factors associated with significantly higher EQ-5D-5L scores were being Aboriginal/Torres Strait Islander (marginal effect = 0.03, P =.021) and recent injecting drug use in the past 12 months. Current HCV infection and liver fibrosis stage were not associated with reduced HRQoL among the study participants. Conclusions: PWID experienced a lower HRQoL compared with the general population. Further research is needed to understand HRQoL in this population to facilitate the development of multifaceted care models for PWID beyond HCV cure and inform health economic analyses for identifying optimal health strategies for PWID.