Background: Emerging adulthood is a pivotal life stage, presenting significant psychological and social changes, such as decreased sociability, depression, and other mental health problems. Previous studies have associated these changes with an unhealthy lifestyle. The 24-h movement guidelines for healthy lifestyles have been developed to promote appropriate health behaviors and improve individual wellness. However, the relationship between adherence to the 24-h movement guidelines and different characteristics of Chinese emerging adults is yet to be explored. This cross-sectional study aimed to investigate the association between adherence to the 24-h movement guidelines and four characteristics (self-exploration, instability, possibilities, and responsibility) of Chinese emerging adults. Methods: Overall, 1,510 Chinese emerging adults aged 18-29 years were included in this study. Each participant completed a self-administered questionnaire that included questions on adherence to the 24-h movement guidelines (physical activity, sedentary behavior, and sleep) and the inventory of dimensions of emerging adulthood. Multivariable logistic regression analysis was employed to investigate the associations between adherence to the 24h movement guidelines and each of the four characteristics. Results: The proportion of participants who adhered to the 24-h movement guidelines was 31.72%. Multiple regression analysis revealed a significantly negative relationship between adhering to more guidelines and instability (β = −0.51, p < 0.001). A statistically significant association was observed between instability and meeting only sedentary behavior (β = −1.27, 95% confidence interval [CI]: [−2.32, −0.24], p = 0.02), sedentary behavior + sleep (β = −1.30, 95% CI: [−2.24, −0.35], p < 0.01), and physical activity + sedentary behavior (β = −1.08, 95% CI: [1.94, −0.21], p = 0.02) guidelines. Further, positive and significant associations were observed between possibilities and meeting the guidelines for only physical activity (β = 0.70, 95% CI: [0.14, 1.27), p = 0.01), only sleep (β = 0.61, 95% CI: [0.01, 1.21], p = 0.04), physical activity + sedentary behavior (β = 0.56, 95% CI: [0.04, 1.07), p = 0.01), and physical activity + sleep (β = 0.76, 95% CI: [0.23, 1.27], p = 0.01). Conclusions: These findings suggest that adherence to the 24-h movement guidelines was associated with instability in Chinese emerging adults. Future studies are warranted to verify our findings to highlight the importance of maintaining a heath lifestyle to promote health in emerging adulthood.