Sexuality education is widely implemented across educational settings, yet no overview has mapped the questionnaires used to evaluate its impact on young people’s sexual health. This scoping review identified and described self-administered questionnaires used to assess the effectiveness of sexuality education interventions targeting young people aged 10–24 years. Following PRISMA-ScR guidelines, we analysed articles published between 2013 and 2025. Eligible studies evaluated a sexuality education intervention and used at least one self-administered questionnaire to assess outcomes. Data were extracted on study characteristics, questionnaire use, measured determinants, and thematic focus. Of 2,206 studies identified, 111 met the inclusion criteria. Most interventions targeted adolescents aged 15 years and older. Reporting on questionnaire development, adaptation and validation was inconsistent. Questionnaires mainly assessed behaviours, knowledge, and attitudes, focusing on sexual practices, HIV/STIs and condom use; few explored sexual pleasure or sexual well-being. Very few studies followed participants beyond 12 months, limiting evidence on sustained changes. Despite their widespread use, self-administered questionnaires remain unevenly documented, limiting comparability across studies and understanding of how sexuality education influences young people’s sexual health. Findings highlight the need for transparent reporting and the development of questionnaires that better align with a positive and holistic approach to sexuality education.