Abstract Background Mental illness is associated with misunderstanding and unfavorable attitude worldwide. The belief in its spiritual nature made traditional healers the main service consultants for mentally ill patients. The present study is a cross-sectional study conducted among 425 main family caregivers of mentally ill patients at Assiut University Hospital. The objective of the study was to assess the caregivers’ knowledge and attitude towards mental illness as well as their health-seeking behavior for their mentally ill relatives. Results The studied caregivers had low scores of knowledge and attitude towards mental illness. Age of the caregivers, their education, and the type of first consulted care and aggressive behavior of the mentally ill relatives were the significant predictors of caregivers’ knowledge and attitude towards mental illness. The majority of caregivers (80.2%) sought advice for the first time from traditional healers. Traditional healers referred only 16.4% of caregivers’ mentally ill relatives to psychiatric care. Conclusion The studied caregivers had poor knowledge and a negative attitude towards mental illness. Traditional healers were the main consulted care. So, increasing awareness of mental illness is highly recommended.