Early onset of alcohol use was associated with alcohol dependence and other health problems. We aimed to identify the prevalence and factors associated with alcohol consumption among adolescents in a rural community in Thailand. A mixed-methods study was carried out in 2021 using an explanatory sequential design. The study enrolled a total of 413 adolescents. On average, young adolescents initiated alcohol consumption at age 13. The lifetime drinking prevalence among adolescents was 60.5%, while the 1-year drinking prevalence was 53.0%. The prevalence of hazardous drinking among current drinkers was 42.0%. Alcohol consumption was associated with females (adjusted prevalence ratio (APR): 1.19; 95% CI 1.01–1.41), age ≥ 16 years (APR: 1.28; 95% CI 1.09–1.50), having close friends consuming alcohol (APR: 1.75; 95% CI 1.43–2.14), night out (APR: 1.93; 95% CI 1.53–2.45), being a current smoker (APR: 1.39; 95% CI 1.15–1.69), and having relationship (with boyfriend/girlfriend) problems (APR: 1.18; 95% CI 1.01–1.38). Qualitative data demonstrated that individual and environmental factors, including friends, family, social media use, and alcohol accessibility, affect alcohol use in this population. Therefore, effective strategies should be implemented across multiple levels of the socio-ecological model simultaneously to alleviate alcohol consumption and attenuate its complications.