IntroductionOpioid misuse among youth is a significant concern given its potential negative consequences; yet youth who use opioids continue to face challenges in seeking treatment. The goal of this study was to understand the demographics, mental health, and substance use and co-occurring concerns of service-seeking youth with opioid use to inform future services and research. MethodsThis study characterized 1769 youth between 14 and 24 years old seeking services at an urban treatment facility in Toronto, Ontario (ON) between 2008 and 2019. Youth who could adequately read English, had no immediate psychiatric service needs, provided research consent, and responded to a question about opioid use history were eligible. Participants provided information on demographics, substance use, mental health, and treatment motivation. ResultsYouth who use opioids were more likely to report challenges with social determinants of health, use more substances, initiate substance use earlier, and use some substances at a higher frequency than youth who do not use opioids. Youth with opioid use reported more co-occurring mental health and substance use concerns than youth with no opioid use. They also endorsed more trauma and a likely PTSD diagnosis. Not being in employment, education, or training and using a higher number of substances positively predicted youth opioid use. In terms of treatment motivation, youth who use opioids endorsed more internal forms of motivation than youth who do not use opioids. ConclusionsYouth who use opioids have complex social and co-occurring mental health and substance use needs that may be addressed with integrated community-based services. Future research should focus on developing evidence-based opioid treatment programs in this context and other innovative platforms.