Scientific evidence has shown that healthcare clowning can decrease the level of stress and anxiety in pediatric patients. However, little attention has been devoted to the potentially beneficial impact of clown visits in the child and adolescent psychiatry setting. Therefore, this pilot study aims at investigating short-term effects of clown visits by RED NOSES Clowndoctors Austria on stress and mood levels of children and adolescents in psychiatric care. The sample will consist of approximately 50 children and adolescents in inpatient psychiatric wards who receive clown visits on a weekly basis over four consecutive weeks. The examined intervention, i.e., the clown visits, is an integral part within the selected psychiatric institutions. Using a non-controlled pre-/post-test design, the level of salivary cortisol and self-reported stress and mood will be measured as primary outcomes before and immediately after each clown visit. Additionally, self-reported effects on care staff at the health care facilities will be assessed based on a questionnaire after each clown visit within the same time period of four weeks. Secondary outcome measures (i.e., health-related quality of life, emotional and conduct problems, perceived chronic stress) will be assessed at baseline and at close-out assessment after the four intervention weeks. Further control variables and potential moderators are included at baseline. Due to the nested data structure, multilevel modeling will be used to analyze the data. To our knowledge, this is the first study to examine the stress-reducing and mood-improving effects of clown visits on inpatients in child and adolescent psychiatry. Results will be relevant for the design of future large-scale RCTs and might provide valuable implications for the use of healthcare clowning to reduce stress and improve mood in children and adolescents in psychiatric care. The study is registered at ClinicalTrials.gov (Identifier: NCT04844398).