Background: Physical activity (PA) and psychosocial interventions are recommended management strategies for cancer-related fatigue (CRF). Randomized trials support the use of mind–body techniques, whereas no data show benefit for homeopathy or naturopathy. Methods: We used data from CANTO (ClinicalTrials.gov identifier: NCT01993498), a multicenter, prospective study of stage I–III breast cancer (BC). CRF, evaluated after primary treatment completion using the EORTC QLQ-C30 (global CRF) and QLQ-FA12 (physical, emotional, and cognitive dimensions), served as the independent variable (severe [score of ≥40/100] vs nonsevere). Outcomes of interest were adherence to PA recommendations (≥10 metabolic equivalent of task [MET] h/week [GPAQ-16]) and participation in consultations with a psychologist, psychiatrist, acupuncturist, or other complementary and alternative medicine (CAM) practitioner (homeopath and/or naturopath) after CRF assessment. Multivariable logistic regression examined associations between CRF and outcomes, adjusting for sociodemographic, psychologic, tumor, and treatment characteristics. Results: Among 7,902 women diagnosed from 2012 through 2017, 36.4% reported severe global CRF, and 35.8%, 22.6%, and 14.1% reported severe physical, emotional, and cognitive CRF, respectively. Patients reporting severe global CRF were less likely to adhere to PA recommendations (60.4% vs 66.7%; adjusted odds ratio [aOR], 0.82; 95% CI, 0.71–0.94; P=.004), and slightly more likely to see a psychologist (13.8% vs 7.5%; aOR, 1.29; 95% CI, 1.05–1.58; P=.014), psychiatrist (10.4% vs 5.0%; aOR, 1.39; 95% CI, 1.10–1.76; P=.0064), acupuncturist (9.8% vs 6.5%; aOR, 1.46; 95% CI, 1.17–1.82; P=.0008), or CAM practitioner (12.5% vs 8.2%; aOR, 1.49; 95% CI, 1.23–1.82; P<.0001). There were differences in recommendation uptake by CRF dimension, including that severe physical CRF was associated with lower adherence to PA (aOR, 0.74; 95% CI, 0.63–0.86; P=.0001) and severe emotional CRF was associated with higher likelihood of psychologic consultations (aOR, 1.37; 95% CI, 1.06–1.79; P=.017). Conclusions: Uptake of recommendations to improve CRF, including adequate PA and use of psychosocial services, seemed suboptimal among patients with early-stage BC, whereas there was a nonnegligible interest in homeopathy and naturopathy. Findings of this large study indicate the need to implement recommendations for managing CRF in clinical practice.