Adolescence is a critical period for establishing lifelong health behaviors; yet in Lebanon, limited data exist on the prevalence of risk factors among this demographic. Objective: This study aims to assess alcohol consumption, dietary habits, physical activity, mental health, and smoking behaviors among Lebanese adolescents aged 13–17 years, with a focus on gender and school-type differences. Methods: A cross-sectional analysis was conducted in Lebanon between March and July 2022 using the Global School-based Student Health Survey (GSHS) questionnaire. A representative sample of students from public and private schools participated in the survey, with key variables analyzed to identify significant patterns and disparities. Results: Our findings reveal that 6.3% of adolescents consumed alcohol, with males reporting a higher prevalence and earlier initiation (p = 0.003). Gender differences were evident in dietary habits, where males were more likely to consume sugary drinks (p = 0.04) and have consistent breakfast habits (p = 0.003). Adolescents from private schools exhibited distinct dietary behaviors, including lower milk consumption (p < 0.001) and higher fatty food intake (p = 0.008). Males were also more physically active and reported better mental health outcomes compared to females (p = 0.004). Smoking behaviors showed that males smoked more frequently, while private school students reported smoking less. No significant difference was observed in bullying experiences between genders or school types. Conclusions: The study highlights critical health behaviors among Lebanese adolescents, with significant variations by gender and school type. These findings underscore the need for targeted interventions to address the identified risk factors and promote healthier behaviors in this population.