This systematic review aimed to synthesize qualitative research on parents' psychological experiences following their child's diagnosis of congenital heart disease (CHD). A systematic search of six electronic databases (CINAHL, Embase, MEDLINE, PsycINFO, PubMed and Web of Science) was completed, inclusive of all years up to May 2022. Any included articles were synthesized using thematic synthesis and appraised using the Critical Appraisal Skills Programme Qualitative Checklist. Twenty-six articles were included. Four main themes, and 11 subthemes, emerged from the synthesis. Theme 1 (unpreparedness for the diagnosis) concerned parents' shock, guilt and anger regarding the diagnosis. Theme 2 (the overwhelming reality of CHD) described parental fear about decision-making and the child's prognosis, and the influence of professionals on parents' well-being. Theme 3 (mourning multiple losses) detailed parents' sadness at losing their envisioned pregnancy, birth and parenthood experiences. Theme 4 (redefining hopes to reach an acceptance of CHD) described parents' adjustment to the diagnosis. Receiving a child's CHD diagnosis was a uniquely challenging situation for parents. The findings provided insight into the emotions parents experienced and how they adjusted to the diagnosis psychologically. As parents' experiences were significantly influenced by their interactions with professionals, clinicians should offer compassion, validation and clear information throughout the diagnosis process. [Abstract copyright: © 2023 The Authors. British Journal of Health Psychology published by John Wiley & Sons Ltd on behalf of British Psychological Society.]