Objectives To estimate the one-month prevalence of problematic psychological symptoms among Canadian postsecondary students, and to compare the prevalence by student characteristics. Participants Three samples of students from two postsecondary institutions. Methods In a cross-sectional study conducted in 2017, we measured self-reported problems related to symptoms of depression, anxiety, and stress using questions from the functioning module of the WHO Model Disability Survey. We used modified Poisson regression modeling to compute prevalence ratios (95%CI) to compare the prevalence by student characteristics. Results Our study included 1392 students (participation rate 35%–77%). Across samples, the one-month prevalence of moderate-extreme problems ranged from 50.8%–64.7% for anxiety, 41.2%–60.8% for stress, and 29.4%–43.6% for depression. Such problems were consistently more prevalent among females, poor-quality sleepers, students with food insecurity and those with insufficient social support. Conclusions Significant burden of problems related to psychological symptoms exists within the postsecondary student population and varies by student characteristics.