Parents of children with chronic illnesses experience many challenges on an everyday basis. Interacting with medical staff, coping with their child’s illness, and understanding information about the course of treatment require adequate health literacy (HL) and e-health literacy. The ability to look for, evaluate, and use health information depends on several factors, including socio-demographic and psychological. Cognitive abilities, motivation levels, and personality factors are crucial among the latter. Research has shown that adequate parental HL is associated with better child health, more effective treatment, and higher quality of life. Understanding health-related information enables efficient communication with medical personnel and thus promotes effective use of health services. It appears that parental health competencies are related to the development of pro-health attitudes in children, which, in the long term, can support the process of making good health decisions on their own. Therefore, assessing and developing parental health competencies is extremely important for their children, especially when they have long-term illnesses. It has been shown that an adequate level of HL also contributes to a health-promoting lifestyle, and that developing HL is one of the most important tasks of disease prevention and health promotion. The main aim of this article is to review the research results on the determinants and importance of health and e-health competencies of parents of children with chronic illnesses.