Background: Medication non-adherence among children with mental disorders (MD) is frequent. Objectives: This research examines the association between medication adherence (MA) in children with MD and the perception of satisfaction with the healthcare received. Methods: A cross-sectional, descriptive, and analytical study was carried out; the survey method was applied to 800 participants who attended from January 2018 to January 2020 at two Children’s Psychiatric Hospitals in Mexico City. The Morisky-Green test was applied. Moreover, the patient’s perception of their improvement and the reasons for their satisfaction were investigated. A Spearman’s correlation analysis was performed between adherence and variables on the patient’s perception of improvement. Results: Sample of 400 dyads (400 children and their 400 caregivers), children’s sample included 63% boys (n = 252). The most prevalent diagnoses were hyperkinetic disorder, with 51% and 34% with depression. Of the sample, 27% adhered to pharmacological treatment. Statistically significant positive correlations were found between adherence and perception of improvement with the functioning variable (rs = 0.550, P < 0.001, and improvement with quality of life (rs = 0.206, P < 0.001). Conclusions: Adherence to treatment in children is related to satisfaction in care, and satisfaction is directly related to improve- ment in functionality and quality of care.