Background There is a need to expand clinical pharmacy services to cover the ambulatory pediatric cancer patients. There is a paucity of published literature describing pharmacy services in this setting. Objective To describe the development, implementation and the reported interventions of a clinical pharmacy service in the outpatient pediatric hematology-oncology clinics at a comprehensive cancer center in Jordan. Methods A stepwise approach was followed to develop and implement the described service. Four goals were set for the service comprising (1) ensure safe medication use (2) improve patient and caregiver education (3) enhance efficiency in medication distribution (4) facilitate the continuity of care across the inpatient and outpatient settings. The interventions collected were categorized into four major classes: clarification, safety, therapeutic and education. Results A total of 939 interventions were reported. Safety interventions were the highest with 500 (53%), followed by education 247 (26%), clarification 113 (12%) and therapeutic 79 (9%). The most common single interventions were patient counseling 247 (26%) and chemotherapy evaluation 229 (24%). Less frequent interventions were drug interactions and adverse drug reactions with 10 (1%) each. Conclusion Developing pediatric hematology-oncology clinical pharmacy services to cover the outpatient setting is essential to ensure continuity of care and to optimize therapeutics.