This study examined the associations between violence victimization, homelessness, and severe mental illness (SMI) among people who use opioids (PWUOs) in three U.S. cities. We analyzed data from a cross-sectional survey conducted from May 2019 to February 2020 across three study sites: Los Angeles, CA; Las Vegas, NV; and Atlanta, GA. We used multivariable regressions to examine how multiple victimizations and housing situation are associated with SMI. Based on K-6 scale, nearly half (44.2%) were screened positive for SMI. Meanwhile, 69.7% of the participants reported experiencing some kind of violence in their lifetime, and more than half (51.9%) reported experiencing recent violence (in the past 6 months). The most common form of lifetime violence was emotional (59.5%), followed by physical and intimate partner violence (IPV) (56.1 and 34.9%, respectively), and 34.9% of all participants reported experiencing multiple forms of victimization in the past 6 months. Participants who reported homelessness were more likely to report having experienced recent violence victimization ( p < .001). In multivariable models, experiencing recent victimization was significantly associated with SMI (adjusted odds ratio (AOR) = 1.85, 95% confidence interval [CI] [1.46, 2.38]), as was homelessness (AOR = 1.57, 95% CI [1.15, 2.14]), after adjusting for study covariates. Among those with moderate and SMI ( n = 927), only 22% were currently receiving mental health services, and those who reported having experienced any forms of violence in the past 6 months were more likely to utilize mental health services than those who had not experienced any recent violence victimization (25 vs. 17.9%, p < .05). To improve mental health and wellness among this high priority population, mental health facilities and syringe service programs may consider screening for experiences of violence and using trauma-informed mental health approaches. Harm reduction interventions must be responsive to the diverse individual and structural-level needs of PWUOs, especially those experiencing homelessness and housing insecurity. Holistic strategies and services are needed to meet the social and structural needs of this population.