The study developed a core set of outcomes (COS-TCM-RA) for traditional Chinese medicine (TCM) clinical trials in the treatment of rheumatoid arthritis (RA) to reduce heterogeneity in outcome measurement and reporting. The systematic review included 2,959 records from which 69 studies were selected and extracted 52 unique results. Semi-structured interviews with patients and a three-round online Delphi survey with experts helped identify and prioritize the most important outcomes. The final COS includes physician assessment of global status, clinical laboratory tests, radiographic assessment, signs and symptoms, quality of life, and safety events including syndromes and adverse events. This set integrates internationally recognized RA assessment tools with patient-reported outcomes and specific TCM measures. COS-TCM-RA thus provides a standardized and multidimensional framework to improve the quality of clinical trials, comparability of results, and support the integration of TCM into evidence-based medicine.