Background: Appendicitis remains one of the most common surgical conditions in children, with surgical appendectomy being the standard treatment. However, the complications from surgery prompt interest in nonoperative management and accurate diagnostic methods. Objective: This study aims to evaluate the role of ultrasonography in differentiating simple from complicated appendicitis in children, improving diagnostic accuracy and reducing unnecessary surgery. Methods: A prospective observational study was conducted at the Paediatric Surgery Department, Mymensingh Medical College Hospital, from January 2021 to June 2022. The study involved 100 children diagnosed with acute appendicitis via ultrasound. Inclusion and exclusion criteria were followed, and informed consent was obtained from all participants. The clinical data, ultrasonographic findings, and histopathological results were collected, and diagnostic accuracy was evaluated using sensitivity, specificity, and predictive values. Results: Out of 100 patients, 68% were diagnosed with simple appendicitis and 32% with complicated appendicitis byultrasonography. Histopathological analysis confirmed 42% simple and 58% complicated cases. The mean age was 10.14 ± 4.66 years. The sensitivity of ultrasonography in identifying complicated appendicitis was 44.83%, while its specificity was 85.71%. The positive predictive value (PPV) was 81.25%, and the negative predictive value (NPV) was 52.94%. Statistical analysis revealed a p-value of 0.001, indicating significant differences between the groups. Standard deviation for age was calculated as 4.66, reflecting a spread in patient age distribution. Conclusion: Ultrasonography, though useful, should not be relied upon alone to differentiate between simple and complicated appendicitis. A combination of clinical, laboratory, and ultrasonographic findings is essential for optimal diagnosis.