Background: Natural disasters may physically and psychologically affect individuals and their surrounding community. This study determines the prevalence of post-traumatic stress (PTS) symptoms and its association with maladaptive trauma-related cognition and resilience among adolescents post-earthquake. Materials and Methods: Data were collected, in this cross-sectional study, during an intervention program post-earthquake held in a state high school located at Lombok, Indonesia. The study sample engaged students 14-19 years of age using the purposive sampling method. The questionnaires used to measure PTS symptoms, maladaptive trauma-related cognition, and resilience were Children's Revised Impact of Event Scale-13 (CRIES-13), Child Post-Traumatic Cognitions Inventory (CPTCI), and Child and Youth Resilience Measure-Revised (CYRM-R), respectively. Results: The prevalence of PTS symptoms was 69.9%. Among the respondents, 61.37% were female and 56.48% had mothers with lower educational levels. Using multiple linear regression, the final predictors of PTS symptoms were excessive reactions (e.g., wailing loudly, miserable shrieking) of proxy during earthquake (β = 3.283, p = 0.005), maladaptive trauma-related cognition (β = 0.224, p = 0.002), and resilience (β = 0.192, p < 0.001) with female gender (β = 7.350, p < 0.001) as a control variable. Through simple linear regression, victims who witnessed injury or death during the earthquake (p = 0.003), had a proxy died during the earthquake (p = 0.01), and trapped victims or those who had difficulty escaping (p = 0.01) were identified to potentially predict the occurrence of PTS symptoms, warranting further study. Conclusion: The presence of excessive proxy reactions during the earthquake, maladaptive trauma-related cognition, and resilience in adolescents exposed to a natural disaster are worth targeting and prioritizing in future post-disaster interventions.