Background: Cigarette smoking usually commences during adolescence and continues into adult life. The aim of the present study was to assess the effect of peer-led intervention on cigarette smoking knowledge, attitude and behaviour of in-school adolescents’ in Sokoto metropolis, North-west, Nigeria. Method and Material: This was a quasi-experimental study, conducted in 3 stages using a study and control group. A total of 114 students each were selected into both groups by two-stage sampling technique. Two peer led health education interventions were administered to respondents in the study group after which questionnaires was administered to both groups. Data was analysed using SPSS, all tests were conducted in 2 tails, and level of significance was 5%. Results: In the study group, the proportion of respondents with adequate cigarette smoking knowledge increased from 75.4% to 97.2% (P=0.000), there was a reduction in the proportion of respondents who supported cigarette being sold to minors (P=0.000), which was significant and there was an increase in the proportion of respondents who would leave a place where cigarette is being smoked (P=0.000). Conclusion: The peer-led intervention was effective at improving respondents’ cigarette smoking related knowledge, attitude and behaviour. A sustained health education program should be set up in schools.