Backgrounds: In Indonesia, outdoor tobacco advertising remains widespread, particularly in urban settings, with strategic placement near educational institutions. Such proximity significantly increases adolescents’ exposure to tobacco marketing, potentially influencing their smoking behaviors. Objectives: This study aimed to evaluate the density, quantity, and size of outdoor tobacco advertisements near schools in Medan City, and to examine their association with students’ smoking behavior. Methods: A total of 3,820 students from 160 schools in Medan City were included in this cross-sectional study. This study conducted interviews using structured questionnaires and measured coordinates using the GPS Waypoints mobile phone application. Spatial analyses were conducted using QGIS version 3.19 to map the distribution of advertisements within 500- and 1000-meter buffer zones around schools. Behavioral data were analyzed using JASP version 19, employing logistic regression to assess the relationship between advertising exposure and smoking behavior with CI 95%. Results: A total of 437 students (11.4%) reported smoking; most students (81.3%) were exposed to tobacco advertisements near educational institutions, with banners (62.1%) and posters (11.4%) being the most common forms of advertisement. Students were much more likely to smoke when they thought cigarettes were affordable (OR=12.51; CI: 4.87–32.13), socially acceptable (OR=8.49; CI: 3.67–19.63), and influenced by their peers (OR=16.34; CI: 7.48–35.72). Conclusions: Cigarette companies are actively promoting cigarettes using outdoor advertisements in Medan City. Cigarette companies actively promote their products by placing banners and posters around schools within a 500-meter radius. Research has proven a correlation between students’ exposure to tobacco advertisements and their smoking behavior. © This work is licensed under a Creative Commons Attribution-Non Commercial 4.0 International License.