To evaluate the potential of a 60-minute sexuality diversity workshop to address bullying in secondary schools.Students completed pre- and post-workshop questionnaires. Descriptive statistics were used to summarise results with pre- to immediate post-workshop changes compared using t-tests. Thematic analysis was used to analyse open-ended questionnaire responses.We had 229 students (mean age 13.7 years) attending 10 workshops participate in the study. Three-quarters of students thought the workshop would reduce bullying in schools, and over 95% of the participants thought that other secondary schools should offer the workshop. There was a significant increase in valuing (p < 0.001) and understanding (p < 0.001) sexuality-diverse individuals (e.g. lesbian, gay and bisexual people), between the pre- and post-workshop results. School climates were largely perceived to be 'hard' and included 'bullying/mocking' of sexuality-diverse students; however, many individual students reported a desire to be supportive of their sexuality-diverse peers.Sexuality-based bullying is commonplace in secondary schools. This form of bullying is associated with depression and suicide attempts. Reducing sexuality-based bullying is very likely to have a positive impact on the mental health of young people. Brief workshops, as a part of a wider suite of interventions, have some potential to create safer school environments.