Abstract Purpose A setting-sensitive instrument for assessing Quality of Life (QoL) in Telemedicine (TM) was unavailable. To close this gap, a content-valid “add-on” measure was developed. In parallel, a brief index was derived featuring six items that summarise the main content of the multidimensional assessment. After pre- and pilot-testing, the psychometric performance of the final measures was investigated in an independent validation study. Methods The questionnaires were applied along with other standardised instruments of similar concepts as well as associated, yet disparate concepts for validation purposes. The sample consisted of patients with depression or heart failure, with or without TM (n = 200). Data analyses were aimed at calculating descriptive statistics and testing the psychometric performance on item, scale, and instrument level, including different types of validity and reliability. Results The proposed factor structure of the multidimensional Tele-QoL measure has been confirmed. Reliability coefficients for internal consistency, split-half, and test-retest reliability of the subscales and index reached sufficient values. The Tele-QoL subscales and the index demonstrated Rasch scalability. Validity of both instruments can be assumed. Evidence for discriminant construct validity was provided. Known-groups validity was indicated by respective score differences for various classes of disease severity. Conclusion Both measures show convincing psychometric properties. The final multidimensional Tele-QoL assessment consists of six outcome scales and two impact scales assessing (un-)intended effects of TM on QoL. In addition, the Tele-QoL index provides a short alternative for outcome assessment. The Tele-QoL measures can be used as complementary modules to existing QoL instruments capturing healthcare-related aspects of QoL from the patients’ perspective.