Background <p>This study aimed to systematically identify, synthesize, and evaluate measurement properties of patient-reported outcome measures (PROMs) of eHL in adult populations.</p> Method <p>A systematic review was conducted, considering studies reporting the development or validation of eHL instruments for adult populations. Four databases and grey literature were searched from January 2000 to 2024, with additional website searches up to 2022. Quality assessment, data analysis and synthesis followed the COSMIN methodology and findings were reported according to PRISMA 2020 guidelines. The GRADE framework was used to assess evidence quality.</p> Results <p>A total of 8558 citations were identified. Seven instruments, 89 articles and 3 reports were included in this review. The HL₁₉-DIGI, DHLI, TeHLI, eHLQ, eHLA, and Lisane demonstrated sufficient ratings for aspects of content validity, albeit with varying levels of evidence, ranging from very low to high. Five instruments showed sufficient ratings for structural validity and internal consistency, but evidence on their reliability was insufficient. No information on responsiveness was mentioned in articles. The HL19-DIGI, DHLI, eHEALS, and eHLQ were the most frequently investigated instruments.</p> Conclusion <p>This review identified 17 eHL instruments, of which seven demonstrated adequate content validity. However, insufficient evidence exists regarding psychometric properties for widespread implementation. It is strongly recommended that the content of these instruments be updated to reflect patients’ evolving use of eHealth services, and that further psychometrics evaluations be conducted systematically.</p> Systematic review registration <p>PROSPERO CRD42021232765.</p>