BackgroundInternationally, the need for appropriately structured, high-quality care in psycho-oncology is more and more recognized and quality-oriented care is to be established. Quality indicators are becoming increasingly important for a systematic development and improvement of the quality of care. The aim of this study was to develop a set of quality indicators for a new form of care, a cross-sectoral psycho-oncological care program in the German health care system.MethodsThe widely established RAND/UCLA Appropriateness Method was combined with a modified Delphi technique. A systematic literature review was conducted to identify existing indicators. All identified indicators were evaluated and rated in a two-round Delphi process. Expert panels embedded in the Delphi process assessed the indicators in terms of relevance, data availability and feasibility. An indicator was accepted by consensus if at least 75% of the ratings corresponded to category 4 or 5 on a five-point Likert scale.ResultsOf the 88 potential indicators derived from a systematic literature review and other sources, 29 were deemed relevant in the first Delphi round. After the first expert panel, 28 of the dissented indicators were re-rated and added. Of these 57 indicators, 45 were found to be feasible in terms of data availability by the second round of expert panel. In total, 22 indicators were transferred into a quality report, implemented and tested within the care networks for participatory quality improvement. In the second Delphi round, the embedded indicators were tested for their practicability. The final set includes 16 indicators that were operationalized in care practice and rated by the expert panel as relevant, comprehensible, and suitable for care practice.ConclusionThe developed set of quality indicators has proven in practical testing to be a valid quality assurance tool for internal and external quality management. The study findings could contribute to traceable high quality in cross-sectoral psycho-oncology by providing a valid and comprehensive set of quality indicators.Trial registration“Entwicklung eines Qualitätsmanagementsystems in der integrierten, sektorenübergreifenden Psychoonkologie—AP “Qualitätsmanagement und Versorgungsmanagement” zur Studie "integrierte, sektorenübergreifende Psychoonkologie (isPO)" a sub-project of the “integrierte, sektorenübergreifende Psychoonkologie (isPO)”, was registered in the German Clinical Trials Register (DRKS) (DRKS-ID: DRKS00021515) on 3rd September 2020. The main project was registered on 30th October 2018 (DRKS-ID: DRKS00015326).Supplementary InformationThe online version contains supplementary material available at 10.1186/s12913-023-09604-3.