Objectives: Health-related quality-of-life (HRQoL) instruments for cardiovascular diseases (CVD) have been commonly used to measure important patient-reported outcomes (PROs) in clinical trials and practices. This study aimed at systematically identifying and assessing the content validity of CVD-specific HRQoL instruments in clinical studies. Methods: The research team searched Cumulative Index to Nursing and Allied Health Literature, Embase, and PubMed from inception to January 20, 2022. The research team included studies that reported the development and content validity for CVD-specific instruments. Two reviewers independently assessed the methodological quality using the Consensus-based Standards for the Selection of Health Measurement Instruments methods on evaluating content validity of PROs. Content analysis was used to categorize the items included in the instruments. Results: The research team found 69 studies reporting the content validity of 40 instruments specifically developed for CVD. Fourteen (35.0%) were rated "sufficient" with very low to moderate quality of evidence. For PRO development, all instruments were rated "doubtful" or "inadequate." Twenty-eight (70.0%) instruments cover the core concepts of HRQoL. Conclusions: The quality of development and content validity vary among existing CVD-specific instruments. The evidence on the content validity should be considered when choosing HRQoL instrument in CVD clinical studies and health economic evaluations.