Adolescence is a critical period marked by significant physical and psychological changes, yet there is limited understanding of suicidal behaviors among adolescents in Bangladesh. To address this gap, the MeLiSA study utilizing a two-stage stratified cluster sampling approach was conducted to investigate the prevalence and associated factors of suicidal ideation, plans and attempts among adolescents. A total of 1,496 participants were recruited from urban and rural areas, and their socio-demographic characteristics and data on smoking, alcohol use, depression, anxiety and insomnia were obtained. Chi-square and Fisher’s exact tests were used for univariate analyses, followed by multivariable logistic regression to identify factors associated with suicidal behaviors. The findings revealed that 6.8% reported experiencing lifetime suicidal ideation, with 2.3% suicide plans and 0.8% suicide attempts. The 12-month prevalence rates were 3.2% for suicidal ideation, 1.5% for suicide plans and 0.6% for suicide attempts. Smoking emerged as a significant predictor of suicidal ideation, plans and attempts, while alcohol use was strongly linked to past-year suicide attempts. Depression was associated with lifetime suicidal ideation, whereas anxiety significantly influenced both lifetime and past-year suicide plans. These results provide valuable insights that could inform evidence-based interventions and policies to address prevalent mental disorders and suicidal behaviors among adolescents in Bangladesh.