Background: Cancer is becoming a major public health problem and a leading cause of death in children worldwide. However, little is known about the epidemiology of childhood cancer in Ethiopia. This study, therefore, assessed childhood cancer incidence patterns in Addis Ababa using the Addis Ababa city population-based cancer registry data from 2012-2017. Methods: Invasive cancer cases diagnosed in ages 0-14 years from 2012-2017 were obtained from the Addis Ababa City population-based Cancer Registry. Cases were grouped according to the International Classification of Childhood Cancer, 3rd edition (ICCC-3) based on morphology and primary anatomic site. Age-standardized incidence rates (ASR) were calculated by the direct method using the world standard population. Results: The overall average annual incidence rate during 2012-2017 in children was 84.6 cases per million, with rates higher in boys (98.97 per million) than in girls (69.7 per million). By age, incidence rates per million increased from 70.8 cases in ages 0-4 years to 88.4 cases in ages 5-9 years to 110.0 cases 10-14 years. Leukemia was the most common childhood cancer in both boys (29.1%) and girls (26.8%), followed by lymphoma in boys (24.7%) and renal tumours (13.1%) in girls. The overall cancer incidence rate decreased from 87.02 per million in 2012 to 51.07 per million in 2017. Conclusion: The burden of childhood cancer is considerably high in Addis Ababa, and its profile is generally similar to those from other parts of sub-Saharan Africa except that renal tumour is the 2nd most commonly diagnosed cancer in girls in Addis Ababa. Future studies should examine risk factors for the occurrence of childhood cancer in Addis Ababa and other parts of Ethiopia.