Even though teachers are key figures of a program's effectiveness, most intervention studies have not focused explicitly on the effects of antibullying programs at teacher level. We conducted a meta‐analysis into the effects of school‐based antibullying programs on determinants of teacher intervention, including teachers’ attitudes towards bullying, their self‐efficacy and knowledge regarding intervention strategies, and the effects on teachers’ bullying intervention itself. Following the PRISMA guidelines, 13 peer‐reviewed papers were retrieved that reported outcomes on teachers, staff, and students (N = 948, 2,471, and 138,311, respectively). Antibullying programs had a significant moderate effect on determinants of teacher intervention (g = 0.531) and a significant small to moderate effect on teacher intervention in bullying situations (g = 0.390). Results of the meta‐analysis indicate that the effectiveness of antibullying programs may increase when components are included to reinforce teachers’ attitudes, subjective norms, self‐efficacy, knowledge, and skills towards reducing bullying in the school.