Inadequate intake of macro- and micronutrients or low dietary diversity can lead to nutritional problems among adolescents. This study aimed to examine the association between social environment, body image, and dietary diversity among senior high school students in Pekanbaru, Indonesia. This quantitative cross-sectional study involved 223 students selected using simple random sampling from two senior high schools in Pekanbaru. Data were collected using a structured questionnaire covering sociodemographic characteristics, social environment, body image, nutritional knowledge, and household food security. Dietary diversity was assessed using a 24-h dietary recall and the Individual Dietary Diversity Score. Data were analyzed using univariate, bivariate (Chi-square), and multivariate (multiple logistic regression) analyses. Overall, 43.5 % of adolescents had low dietary diversity, while 32.7 % were exposed to an unfavorable social environment and 41.3 % reported a negative body image. Multivariate analysis showed that adolescents in a favorable social environment were more than twice as likely to have a diverse diet compared to those in an unfavorable environment (POR=2.08; 95 % CI: 1.15-3.74; p=0.015). Adolescents with a positive body image were 1.72 times more likely to consume a diverse diet than those with a negative body image, indicating a potential association (POR=1.72; 95 % CI: 0.97-3.04; p=0.062). A supportive social environment and a positive body image are essential for promoting dietary diversity among adolescents. Interventions should focus on strengthening family and peer support, promoting positive nutrition messages through social media, and encouraging the consumption of fruits, vegetables, legumes, and dairy products through school- and family-based nutrition education programs. © 2026 the author(s)