Cancer-related fatigue is a highly prevalent and distressing symptom that negatively affects the quality of life of patients in all stages of cancer, including survivors. The Cancer Fatigue Scale (CFS) is a 15-item multidimensional instrument with the potential to enhance comprehension of fatigue. This study aimed to translate the original English version of the CFS into Korean and establish the validity and reliability of the translated version. A cross-sectional descriptive design was used to translate and validate the CFS in Korean. Factor analyses were performed to understand and establish construct and convergent validity with the Brief Fatigue Inventory (BFI), Functional Assessment of Chronic Illness Therapy-Fatigue (FACT-F), and European Organization for Research and Treatment of Cancer Quality of Life Questionnaire Core-30 (EORTC QLQ-C30). The CFS demonstrated good internal consistency (Cronbach’s alpha coefficient for all 15 items = 0.806); the Kaiser–Meyer–Olkin Measure of Sampling Adequacy was found to be 0.897, and Bartlett’s test of sphericity was significant (p< 0.001). Moderate correlations were found between BFI, FACT-F, and EROTC QLQ-C30, indicating moderate validity. However, there were differences in factorial validity between the original scale and the Korean version, demonstrating a need for further testing in a homogenous population of cancer patients. The findings of this validation and reliability study showed that the Korean version of the CFS is a concise, reliable, feasible, and practical tool for evaluating the multidimensional aspects of cancer-related fatigue in patients with cancer.