Recent research has shown that creative self-concept might be not only a path to people's creativity but also a path to their positive affect. This study proposed and examined the underlying mechanisms of how creative self-concept is associated with positive affect through the mediating role of people's daily creative behavior and creative self-assessment. We recruited 101 Chinese undergraduate students to report their creative behavior, creative self-assessment, and experiences of positive emotion states each day for 14 days. A multilevel structural equation model was conducted. Results confirmed the mediating role of creative self-assessment and the chain-mediating role of creative behavior and creative self-assessment between creative self-concept and positive affect. The direct effect of creative behavior on positive affect was not verified. These findings highlight the role that creative self-concept plays in everyday activities and everyday well-being and show the importance of creative self-assessment in creativity education and mental health care.