Abstract Objective To translate the Leuven Knowledge Questionnaire for Congenital Heart Disease into Brazilian Portuguese and to validate its psychometric properties with parents and family caregivers of children with congenital heart disease. Method This was a six-step methodological study, including the translation, synthesis, back-translation, evaluation of the version translated by the committee of experts, pre-testing, and validation, for which two pilot tests were used including the think-aloud protocol. The content validity index and the frequency of socioeconomic data were calculated in a statistical programming environment. Results In content validation, the instrument showed good applicability among experts, with average content validity index of 0.8-1, while kappa agreement analysis was between 0.76 to 1; both results were considered adequate for validation. Conclusions The results suggest reliability among the evaluators, indicating the instrument's accuracy and the possibility of using it to assess the knowledge of parents and family caregivers about congenital heart disease.