Background: Studies investigating risks of common mental disorders (CMDs) in refugee youth are sparse. The current study examined health care use due to CMDs in unaccompanied and accompanied refugee youth and Swedish-born, and the role of education and residency duration. Methods: This longitudinal cohort study included 743,671 individuals (whereof 33,501 refugees) between 19 and 25 years, residing in Sweden in 2009. Refugees were classified as unaccompanied/accompanied. Risk estimates of CMDs, measured as health care use and antidepressant treatment, between 2010 and 2016 were calculated as adjusted hazard ratios (aHR) with 95% confidence intervals (CI). Highest attained education in 2009, and residency duration were examined as potential modifiers. Results: Compared to Swedish-born youth, refugees had a lower risk of treated major depressive and anxiety disorders (aHR): 0.73 (95% CI 0.68–0.78) and 0.74 (95% CI 0.70–0.79) respectively), but a higher risk for posttraumatic stress disorders (PTSD). Compared to Swedish-born, unaccompanied had an 8-fold elevated risk for PTSD (aHR: 8.40, 95% CI 6.16–11.47) and accompanied refugees had a nearly 3-fold risk of PTSD (aHR: 2.78, 95% CI 2.29–3.37). Rates of PTSD decreased with years spent in Sweden. The risk of CMDs decreased with increasing education. Limitations: The study lacked information on pre-migration factors. There may further be a potential misclassification of untreated CMDs. Conclusion: Refugees had a lower risk of treated depressive and anxiety disorders but a higher risk for PTSD. In refugees, the rates of anxiety disorders increased slightly over time whereas the rates of PTSD decreased. Last, low education was an important predictor for CMDs.