We described the population pharmacokinetics of olanzapine in a cohort of 45 children. Olanzapine is an atypical antipsychotic indicated for treatment schizophrenia and bipolar I disorder but is commonly prescribed off-label to treat delirium and agitation in critical care settings. Our analysis represents the first of its kind to describe the pharmacokinetics of olanzapine in children ranging from infants to adolescents. Olanzapine’s half-life was found to exhibit a U-shaped pattern across the developmental age range. Simulations from our final model were used to propose a preliminary dosing strategy for children. Our developed dosing scheme used weight‐normalized doses for children ≤6 months postnatal age or <15 kg and fixed doses for children ≥15 kg. The manuscript was published in the British Journal of Clinical Pharmacology.