The purpose of this paper is to report the process of co-production and feasibility testing of a novel, gender-transformative RSE programme with young male offenders to encourage positive healthy relationships, gender equality, and future positive fatherhood. A needs analysis highlighted the men’s interest in RSE along with the appeal of film drama and peer-group-based activities. In the co-production stage, scripts were developed with the young men to generate tailored film dramas and associated activities. This co-production led to “If I Were a Dad”, an eight-week programme comprising short films and activities addressing masculinities, relationships, sexual health and future fatherhood. A feasibility pilot of the programme demonstrated acceptability and feasibility of delivery in two prison sites. The programme warrants further implementation and evaluation studies.