Despite rising rates of sexually transmitted infections (STIs) and inequitable access to education and services, few studies have addressed the unique sex education needs of newcomer youth in Canada and other increasingly demographically diverse Western countries. This study involved the design, implementation and evaluation of a novel and innovative participatory action research project, SExT: Sex Education by Theatre. SExT is a theatre-based, culturally empowering, peer education intervention piloted in a multicultural area of Toronto. Young people were trained as peer educators through participation in theatre-based workshops culminating in the performance of a new play for peers. Mixed methods evaluation involved surveys, focus groups, peer interviews and arts-based data collection. Paired-samples t-tests were conducted to investigate changes in sexual health self-efficacy (protection, STI/HIV testing, sexual limit-setting) over three time-points (pre, post, 4-month follow-up). Thematic analysis was used to gain a deeper understanding of outcomes. Quantitative analysis demonstrated significant improvements in outcome measures from pre- to post-intervention that were maintained at follow-up. Qualitative data indicated increased sexual health self-efficacy attributed to SExT. Pilot study findings suggest that SExT may serve as a model for sexual health interventions in areas populated by newcomer and other priority youth groups.