Introduction: The mandibular gonial angle is a craniofacial parameter that reflects anatomical adaptation influenced by growth processes, masticatory function, and sexual dimorphism, making it relevant for age and sex estimation. This parameter has been widely applied in dental and craniofacial studies. However, evidence from community based Indonesian populations remains limited. Population specific data are important for improving the accuracy and applicability of craniofacial indicators. This study aimed to evaluate mandibular gonial angle characteristics for age and sex estimation in Semampir District, Surabaya. Methods: This analytical observational study employed a cross-sectional design involving 100 adults aged 21–50 years from Semampir District, Surabaya, consisting of 50 males and 50 females. Mandibular gonial angle measurements were obtained from digital panoramic radiographs using standardized anatomical landmarks. Bilateral measurements were averaged for analysis. Descriptive statistics were used to summarize gonial angle values, while inferential statistical tests were applied to evaluate differences related to age and sex. Results: Descriptive analysis showed variation in mandibular gonial angle values across different age groups without a consistent age-related pattern. In contrast, a clear difference in mean gonial angle values was observed between the sexes, with female subjects demonstrating higher mean values than male subjects. Statistical analysis showed a statistically significant difference in gonial angle values according to sex (p<0.001), while no statistically significant association was found between age and gonial angle measurements (p>0.05). Conclusion: The mandibular gonial angle demonstrates pronounced sexual dimorphism but limited applicability for adult age estimation in the studied population. These findings suggest that the gonial angle may serve as a supportive craniofacial indicator for sex estimation, while its role in age estimation should be interpreted with caution. Population-specific, community-based data are important for strengthening the forensic and dental applications of craniofacial parameters in Indonesian populations.