Children with acquired brain injury (ABI) often have cognitive and behavioral impairments that affect participation in everyday activities. Among them, executive function (EF) deficits are frequent. Cognitive Orientation to Daily Occupational Performance (CO-OP) is an individualized treatment that teaches cognitive strategies necessary to support successful performance. Few studies have examined the effectiveness of CO-OP in children with EF deficits after ABI. Objectives: to assess whether the use of CO-OP could be of interest in children with EF deficits after ABI, to improve their occupational performance, their executive functioning in everyday life and their cognitive processes constituting EF. Methods. This was a single case experimental study with multiple baselines across individuals and behaviors. We included 2 children at least 6 months after severe ABI. The children received 14 individual sessions of the CO-OP intervention. Each child set 3 goals by using the Canadian Occupational Performance Measure; 2 goals were trained and the third was a control goal. The achievement of the goals was measured by using repeated measures of Goal Attainment Scales (GASs). Ecological assessments of EF included the Children's Cooking Task and parent and teacher ratings of the Behavior Rating Inventory of Executive Function (BRIEF) questionnaire. Results: both children improved their performance on both trained goals (and, to a lesser extent, on untrained goals). We found significant improvement on tests of EF and on the BRIEF questionnaire, reflecting executive functioning in everyday life, at home and at school. Conclusions: these results are encouraging and suggest the feasibility and effectiveness of CO-OP for children with EF deficits after ABI. They should be replicated in a larger number of cases. Trial registration: ClinicalTrials.gov (NCT04718688).