Background: Mental health literacy is considered an important factor in promoting professional psychological help-seeking attitudes. However, it is important to clarify the emotional and behavioral factors that underlie this association. Drawing from the ABC model of attitudes and the Health Disclosure Decision-Making Model, this study aimed to examine the mediating role of psychological help-seeking stigma and distress disclosure in the relationship between mental health literacy and professional psychological help-seeking attitudes. Methods: We collected data from 827 participants in seven regions of China (597 female; M_age = 26.019, SD = 5.592 years old) using self-report measures, including the Mental Health Literacy Scale, Questionnaire of Stigma for Seeking Professional Psychological Help, Distress Disclosure Index, and Attitudes Toward Seeking Professional Psychological Help-Short Form. A chain mediation model was built to examine the relationships among mental health literacy, psychological help-seeking stigma, distress disclosure, and professional psychological help-seeking attitudes. Results: The results of the analyses showed a positive association between mental health literacy and professional psychological help-seeking attitudes, with psychological help-seeking stigma and distress disclosure playing mediating roles in this relationship. Furthermore, even after controlling for participants’ age, gender, and education, the chain mediation effect of psychological help-seeking stigma and distress disclosure on the relationship between mental health literacy and professional psychological help-seeking attitudes was observed among the Chinese population. Conclusions: These findings underscore the significance of mental health literacy in shaping professional psychological help-seeking attitudes, while emphasizing the need to account for psychological help-seeking stigma and distress disclosure when examining this association. Additionally, the model proposed in this study provides a valuable framework for promoting the utilization of professional mental health services.