Sleep quality tends to be poor among emerging adults (ages 18–25). Poor sleep quality has short- and long-term health consequences, including decreases in cognitive function and mood and reductions in immune function. Trait mindfulness, or observing experiences without becoming emotionally aroused or passing judgment, has been linked to increased sleep quality in emerging adults, but little research attention has examined mechanisms that may explain this relationship. Because mindfulness has been associated with reductions in both anxiety and depression, and anxiety and depression are associated with more sleep disturbances, it is possible that mindfulness may operate on sleep quality through reductions in both anxiety and depressive symptoms. This study examined the links between mindfulness, depressive symptoms, anxiety, and sleep quality in 283 emerging adults. Results indicated that higher levels of mindfulness were related to better sleep quality through lower levels of anxiety and depressive symptoms. Post hoc analyses indicated that mindfulness was also associated with fewer sleep disturbances and less daytime sleep dysfunction through lower levels of anxiety and depressive symptoms. However, higher levels of mindfulness were associated with longer sleep duration, better sleep efficiency, and better subjective sleep quality only through fewer depressive symptoms and higher levels of mindfulness were associated with shorter sleep latency only through anxiety. Results suggest that mindfulness may be an effective tool for increasing sleep quality in emerging adults.