Mothers of children with complex congenital heart disease face unique challenges and emotional burdens, while their children go through physical and psychological difficulties during disease progression. In this study, we aimed to explore the in-depth experiences and feelings of mothers facing the prognosis of their children with complex congenital heart disease that was surgically corrected. This is a descriptive qualitative study. We conducted semi-structured, face-to-face interviews with 12 mothers of children with complex congenital heart disease at a tertiary hospital in Seoul, Korea. The interview data were analyzed by content analysis. Participants were mothers aged between 40-58 years whose children were diagnosed with complex congenital heart disease which was surgically corrected. Based on the content analysis, the mothers' experiences and feelings were categorized as immense suffering and adapting to a new life. Under the main categories, the concepts included feeling of abandonment, anxiety with potentially losing their children, having hope, seeking reassurance, being encouraged, and trying to embrace the situation. Mothers who cared for their children with complex congenital heart disease expressed emotions that changed sequentially alongside physical and psychosocial changes in the children. The results of this study are valuable for understanding the experiences and emotions of mothers facing the prognosis of their children with complex congenital heart disease in order to aid in the development of programs that support these mothers.