According to the objectification theory, frequent encounters with sexual objectification will coax people into internalizing a third-party self-perspective and observing themselves through a sexually objectifying lens, a process termed as self-objectification. Previous studies reported that a high level of self-objectification would be detrimental to individuals' physical and mental health, so it is important to explore what factors contribute to the development of self-objectification. At the individual level, cultural orientation is the way in which individuals view the relationship between themselves and the external world, and it includes four types: vertical individualism, vertical collectivism, horizontal individualism and horizontal collectivism. Up to now, little research has explored how cultural orientation at the individual level affects self-objectification, and the results of cross-cultural research on self-objectification are also controversial. Overt narcissism is a personality trait, and previous studies suggested that culture may play an important role in shaping overt narcissism. In addition, overt narcissism affects individuals' body awareness. Several studies showed that overt narcissists think their bodies are attractive and they often have a higher level of self-objectification. In conclusion, first of all, there are controversies in previous cross-cultural studies on the relationship between cultural orientation and self-objectification. Secondly, few researchers have explored the role of overt narcissism in the relationship between cultural orientation and self-objectification. In addition, most studies exploring the influence factors of self-objectification included only female participants, so the relationship between cultural orientation and self-objectification in male groups remains unclear. Herein, this study aims to investigate the relationship between cultural orientation and individual’s self-objectification among Chinese college students, and the mediating role of overt narcissism. In addition, this study further discussed whether the mediation model is consistent across genders. Participants included 1720 college students (556 males and 1164 females) from a certain university. Three questionnaires were used in this study: Narcissistic Personality Inventory, Individualism and Collectivism Scale, and Self-Objectification Questionnaire. These scales had good reliability and validity. All data was analyzed by the software of SPSS 21.0 and Amos 22.0. The results indicated that: (1) Vertical individualism was positively correlated with self-objectification, while vertical collectivism, horizontal individualism and horizontal collectivism were negatively correlated with self-objectification. (2) The mediating effect of overt narcissism was not significant in the relationship between horizontal cultural orientation and self-objectification, while horizontal individualism and collectivism only had a direct effect on self-objectification. Vertical individualism and collectivism can not only significantly predict self-objectification, but also affect self-objectification through the mediating role of overt narcissism. (3) There are significant gender differences in vertical dimension cultural orientation, overt narcissism and self-objectification: Male participants scored significantly higher than female participants on vertical individualism, vertical collectivism and overt narcissism, while female participants scored significantly higher than male participants on self-objectification. The mediating models between vertical cultural orientation and self-objectification have measurement equivalence between genders. These results suggest that self-objectification is affected not only by external social and cultural environments, but also by cultural orientation at the individual level and overt narcissism. This means that individual characteristics also play an important role in the formation and development of self-objectification. Concern for collective goals and interests and concern for building harmonious group relations are associated with lower self-objectification. Overemphasis on the uniqueness of the self and the maintenance of the unique self by means of competition and comparison with others are associated with higher self-objectification. Therefore, from the perspective of constructing the individual-collective relationship, researchers can reduce the level of self-objectification by encouraging individuals to devote themselves to the collective goal in future interventions.