Bullying and cyberbullying are issues that affect the health and development of school-aged children and adolescents. Within the context in which these phenomena occur (i.e., schools), teachers are recognized as essential agents in both the prevention and intervention of reported cases. They are also key figures in antibullying initiatives implemented across various countries. However, there is limited scientific literature in Brazil documenting antibullying actions or interventions led by teachers. Our aim was to develop a brief, culturally adapted, and validated Brazilian version of the Sohanjana Antibullying Intervention Program. This intervention was originally developed at a university in Germany and experimentally applied in Pakistan. An integrative literature review preceded the empirical study to inform decisions and support the discussion. This is a quasi-experimental study that followed the phases of the Integrative Cultural Adaptation Model: information gathering; preliminary adaptation design; feasibility study; adaptation refinement; randomized controlled trial. Two schools served as the empirical sites for data collection—one designated as the experimental school, and the other as the control. In total, 57 teachers (65% women) from both schools participated in the study. Teachers' knowledge and attitudes regarding the study's core phenomena were collected qualitatively. Their responses were analyzed using thematic content analysis through the Requalify.ai platform. The evidence revealed high acceptability of the intervention among participating teachers, as well as their engagement throughout the various stages of the program. Post-intervention comparisons between groups showed that teachers in the intervention group demonstrated greater conceptual clarity and alignment with the scientific literature when describing bullying and cyberbullying. We conclude that the brief Portuguese-language version of the Sohanjana Antibullying Intervention Program, implemented in Brazil, is a useful tool with potential to support schools in preventing bullying and cyberbullying. The results may be useful to support other studies in other contexts of the same nature.