In Aotearoa/New Zealand, sexuality education is one of seven key areas of learning in the Health and Physical Education (HPE) subject area within The New Zealand Curriculum. Since 2015, sexual diversity (lesbian, gay, bisexual identities and perspectives) and gender diversity (transgender; non-binary gender) have been explicitly included in the curriculum guidelines for teaching sexuality education in schools. Based on survey data collected from a convenience sample of 73 participants aged between 16 and 19 years, this study focused on the prevalence of sexuality education provision, its content, and the inclusion of sexuality and gender diversity in the wider school environment. Despite sexuality education being a mandatory part of HPE, only around three-quarters of respondents remembered having been taught it at some point in years 9 and 10. When taught, sexuality education was reported to focus primarily on conventional content areas (e.g. heterosex; biological function) and was therefore not inclusive of sexuality and gender diversity. Inclusion in the wider school environment was also limited, being mainly restricted to easy to implement measures (e.g. allowing same-sex partners at school balls and having a rainbow ally group). The implications of these findings for the development, wellbeing and human rights of young people are discussed.