Background and Objectives: In 1989, the United Nations (UN) General Assembly adopted the United Nations Convention on the Rights of the Child (UNCRC), with a considerable number of the Articles of the Convention being related to the health status of children. Therefore, adhering to and assessing the implementation of the rights of children during hospitalization is a very important step towards child protection. Herein, we attempt to highlight the depth of knowledge of employees working in children’s hospitals with regard to children’s rights as well as the degree of adherence to the UNCRC with respect to hospitalized children.Material and Methods: The target group included all healthcare professionals working in the various general pediatric clinics of the three Children’s Hospitals of the Athens metropolitan area in Greece. We conducted a cross-sectional study, with data collection carried out in February and March 2020, using a structured questionnaire consisting of 46 questions which was handed out to all personnel. For the analysis, we used the IBM SPSS 21.0.Results: A total of 251 individuals participated in the study (physicians 20%, nurses 72%, and other employees 8%). A total of 54.5% of health professionals did not know what the UNCRC is, and 59.6% of them were not even aware that their hospital had rules and a bioethical committee related to clinical research involving children. Lack of awareness or trust of health professionals is also observed for other procedures or supervisory measures such as abuse protocols, complaint control, admission control, etc. With regard to the health system, there are shortcomings or weaknesses in (a) procedures followed with regard to respect for gender and privacy, (b) information on basic services provided by pediatric hospitals (such as recreation, education and free meals during hospitalization), (c) the logistical infrastructure (such as recreational facilities and facilities for the disabled), (d) the possibility of recording complaints, and (e) hospitalizations that were not necessary. A difference emerged concerning the nurses’ responses between the three hospitals, with nurses participating in relevant seminars held in one of the hospitals being significantly more informed.Conclusions: The majority of healthcare personnel seem unaware of basic principles with respect to children’s rights during hospitalization as well as relevant procedures and supervisory measures. Moreover, obvious weaknesses of the health system exist with respect to procedures, services, infrastructure, and complaint recording. There is a need for improved education of health professionals with respect to the implementation of children’s rights in pediatric hospitals.