AbstractBackgroundAdolescent suicide is a global public health concern and the second leading cause of adolescent death worldwide. This study aimed to estimate the burden of adolescent suicidal behaviours and its association with violence and unintentional injury, psychosocial, protective, lifestyle and food security-related factors amongst school-based adolescents across 77 countries in the six World Health Organization (WHO) regions.MethodsThis study comprised a sample of 251 763 adolescents drawn from the latest Global School-based Student Health Survey of school-based adolescents, aged 11–17 years, across 77 countries. Logistic regression analyses were employed to estimate the adjusted effect of independent factors on adolescent suicidal behaviours.ResultsThe population-weighted 12-month prevalence of suicidal ideation (SI), suicidal planning (SP) and suicidal attempts (SA) amongst school-based adolescents was 18, 18 and 16%, respectively. Adolescent suicidal behaviours (i.e. SI, SP and SA) were respectively associated with being physically attacked, physical fighting, high levels of anxiety, feeling lonely, being bullied, lack of parental support, poor peer support, not having close friends and high levels of sedentary behaviours. Overall, these associations also extended to the context of food insecurity across regions and country income groups, where the magnitude of association slightly varied from odds ratios of 1.25 times to 3.13.ConclusionsThe burden of school-going adolescent suicidal thoughts, suicide planning and suicide attempts is of particular concern in low-resource countries. Comprehensive suicide prevention programmes for school-going adolescents in LMICs are needed that address socio-cultural inequities related to violence and unintentional injury, social support and psychological factors, protective, and lifestyle-related factors.