This study aims to understand how gender diversity and gender attitudes are linked to the sexual well-being of young adolescents. Data was collected among 561 adolescents in secondary schools in Flanders and binary logistic regressions were performed. Gender diversity was conceptualized as gender identity, gender expression, sex assigned at birth, sexual orientation and personal gender attitudes. Whereas “like to become a wo/man” and body image were used as measures for sexual well-being. Age and migration were added as covariates.The data illustrates that gender diversity is present among young adolescents and that it can be linked to young adolescent’s body image and liking to become a wo/man. In addition, it shows how diverse sets of gender attitudes are differently associated with sexual well-being outcomes. The findings also suggest the internalization of patriarchal and heterosexual societal norms by the respondents. The results indicate an association between on the one hand gender diversity and gender attitudes and on the other hand adolescent sexual well-being. Furthermore, it suggests that gender transformative research and programs that aim to improve adolescent sexual health and well-being should carefully choose their gender focus and invest in improving gender equity beyond the individual level. Additional research is needed to investigate the association between gender diversity and adolescent sexual wellbeing among diverse sexual well-being conceptualizations and specific groups (gender, ethnic, and others) of young adolescents.