Physical inactivity is a serious public health concern in adolescents from low- and middle-income countries (LMICs). Despite this, only a few multinational studies has investigated correlates of physical activity (PA) in young adolescents in this part of the world. In this study, we identified physical activity correlates using data from the Global school-based Student Health Survey. In total, 142,118 adolescents from 48 LMICs (age 13.8 ± 1.0 years; 49% girls) were included in the analyses. PA was assessed by the PACE+ Adolescent Physical Activity Measure and participants were dichotomised into those who do (60 min of moderate-vigorous PA every day of the week) and do not comply with the World Health Organization recommendations. We used multivariable logistic regression in order to assess the correlates. The prevalence of low PA was 15.3% (95%CI = 14.5%-16.1%). Boys (OR = 1.64; 95%CI = 1.47-1.83) and those who participated in physical education for ≥5 days/week (OR = 1.12; 95%CI = 1.10-1.15) were more likely to meet PA guidelines, while adolescents with food insecurity (OR = 0.85; 95%CI = 0.80-0.90), low fruit and vegetable intake (OR = 0.68; 95%CI = 0.63-0.74), low parental support/monitoring (OR = 0.68; 95%CI = 0.62-0.74), no friends (OR = 0.80; 95%CI = 0.72-0.88), and who experienced bullying (OR = 0.93; 95%CI = 0.86-0.99) were less likely to have adequate levels of PA. There were a few variations in the correlates depending on country-income level. Our data indicate that in adolescents aged 12 to 15 years living in LMICs physical activity participation is a complex and multi-dimensional behavior determined by sociocultural, socio-economic, and policy-related factors. Longitudinal research is needed to confirm/refute the present findings.