INTRODUCTION: There is growing evidence of the benefit of physical activity and mindfulness in breast cancer patients (HC et al. in BMC Complement Altern Med, 2017). Yoga offers a combination of both. The aim of this study was to establish an online yoga program for breast cancer patients and survivors. As the project was launched during the (COVID) pandemic restrictions, we intended to prove effective online yoga as a way to access supportive therapy independently of sanitary issues and geographic locations in rural regions. METHODS: The two main outcomes were quality of life and sleep quality, and both were evaluated by standardized questionnaires (EORTC-QLQ 30 BR 23 and PSQI). Participants (n = 173) had breast cancer or a history of breast cancer and were randomized to either 6 weeks online yoga, twice a week for 45 min or a waiting control group. RESULTS: Our results show improved sleep quality in the PSQI score and improved subitems (dyspnea and physical activity) in the EORTC quality of life score. DISCUSSION: Online yoga seems to be a valid option in supportive therapy for breast cancer patients, as it improves physical fitness, dyspnea and overall sleep quality. It is also safe and cost effective as a remote intervention. TRIAL REGISTRATION: Trial registration number and date of registration for prospectively registered trials: DRKS00029548, 07.07.2022.WHO International clinical trials registry platform number: DRKS00029548. The registration number of the ethical committee CAU in Kiel: D 589/20.