Background: Previous studies on effects of Tai Chi on physical and mental health among college students have lacked an objective measure of sleep quality. This study will address the gaps in the current literature. Purpose: This study examined the effects of 16-week Tai Chi lessons on perceived stress, anxiety, and sleep quality measured with the ActiGraph activity monitor in college students. Methods: Participants were forty-five college students (14 males and 31 females) with mean age of 19 yrs. (SD = 0.548 yrs.) who enrolled in one, 90-min Tai Chi lesson per week for 16 weeks during a fall semester of 2016 at one major public university in Shanghai, China. One week prior to and after the 16-week Tai Chi lessons, the students completed the Perceived Stress Scale (PSS), the Generalized Anxiety Disorder 7-item (GAD-7) Scale. In addition, they wore the ActiGraph Gt3X-BT activity monitor day and night for seven consecutive days to objectively measure their sleep time and quality. Results: The paired t-tests showed no significant changes in the perceived stress and anxiety from the pre-to the post-test (t = −0.429, df = 37, p = 0.670; t = −1.605, df = 37, p = 0.117). The ANOVA with repeated measures revealed no significant main effect of gender, time, and the interaction of them in the perceived stress and anxiety. The paired t-test yielded a significant change in sleep time (t = 2.48, df = 37, p = 0.017). There was no significant main effect of gender and the interaction of time with gender. The paired t-test showed no significant differences in sleep quality over times. Conclusion: Learning and performing one, 90-min Tai Chi lesson weekly for 16 weeks helped the students maintain a manageable level of the perceived stress and anxiety and meet the recommended sleep time and to have a high level of sleep quality while experiencing a moderate level of stress and anxiety over times.