Single-center studies or randomized controlled trials have evaluated the impact of radiotherapy for bone metastases on quality of life (QOL). We investigated the real-world impact of radiotherapy for bone metastases on QOL using nationwide multicenter cohort data. We conducted a prospective observational study at 26 centers in Japan. Of 333 patients who received radiotherapy for bone metastases between December 2020 and March 2021, 232 (70%) were enrolled in the study. Patient-reported QOL was evaluated at enrollment and at two- and six-month follow-up using the European Organization for Research and Treatment of Cancer (EORTC) QOL Questionnaire Core 15-Palliative and the EORTC QOL Questionnaire Bone Metastases module (QLQ-BM22). Possible predictors (patient-, tumor -, and treatment-related factors) of QOL improvement were screened using logistic regression models. QOL scores showed significant improvement at two-month follow-up in seven (global health status/QOL, emotional functioning, pain, insomnia, painful sites, pain characteristics and functional interference) of the 14 scales. Of these seven scales, mean improvement ≥ the minimal clinically important difference (defined by a change of 10 or more on the 0 to 100 scale) was seen in four scales (pain, insomnia, pain characteristics and functional interference). We did not find any predictors of QOL improvement in the functional interference scale of QLQ-BM22. Radiotherapy for bone metastases performed in daily practice is effective in improving some scales of QOL.