There are concerns that radiotherapy for prostate cancer influences health-related quality of life in the long term. Furthermore, it is unclear whether postoperative radiotherapy is associated with a different quality of life due to a higher treatment burden compared to patients having received definitive radiotherapy for prostate cancer. This study enrolled 247 patients with localized or locally advanced prostate cancer who received external radiotherapy between 2011 and 2021. Health-related quality of life was assessed at a median of 63.6 months after radiotherapy using the European Organization for Research and Treatment of Cancer quality of life questionnaire (EORTC QLQ-C30) with 145 patients returning questionnaires (response rate, 58.7%). Four patients treated with adjuvant radiotherapy were excluded due to the small number, resulting in 141 participants who received salvage radiotherapy (70 men) or definitive radiotherapy (71 men). The study compared the quality of life with age- and sex-matched German normative data. Patients completed the questionnaires after a median time of 60.3 and 65.2 months after salvage and definitive radiotherapy. The median patient age was higher in the definitive than in the salvage radiotherapy group (at radiotherapy, 72 vs. 69 years; at the survey, 79 vs. 75 years). Global health status, functional scales (physical, role, emotional, cognitive, and social), and symptom scales were not different between cancer patients of the same age group treated with salvage and definitive radiotherapy. The comparison with age- and sex-matched normative data revealed that salvage and definitive radiotherapy did not impair the global health status in patients of any age group. Physical functioning in patients < 70 years was significantly better in salvage and definitive radiotherapy groups compared to normative data while showing clinical relevance. Yet, social functioning was significantly lower in patients ≥ 70 years of the salvage radiotherapy group compared to normative data, while this difference lacked clinical significance. Regardless of the type of radiotherapy applied, cancer patients had no statistically or clinically relevant higher symptom burden compared to normative data. Quality of life was not clinically relevant influenced by radiotherapy, regardless of whether patients received salvage or definitive radiotherapy. Yet, longitudinal measurements of quality of life after radiotherapy are required to detect fluctuations in quality of life.