Mindfulness, which involves paying attention to present-moment experiences in an open, curious, and accepting manner, has received attention as a possible way to reduce substance use among university students. However, previous research on how mindfulness is related to alcohol use in university populations has yielded mixed findings, and thus far, the relation between dispositional mindfulness and cannabis use in university students is unknown. In the present study, dispositional mindfulness, alcohol use, and cannabis use were assessed in university students (n = 768) using an online survey. Higher dispositional mindfulness was found to be significantly associated with lower levels of alcohol dependence and problems related to alcohol use, and to lower levels of problematic cannabis use. Overall, this demonstrates that students with higher levels of dispositional mindfulness report lower levels of problematic alcohol and cannabis use than students with lower levels of mindfulness. Limitations and future directions are discussed.