Simple Summary: Hyperthermia (HT) is a clinical treatment modality that is used in combination with radiotherapy (RT) and/or chemotherapy (CT) in cancer patients to enhance the effect of ionizing radiation and chemotherapeutic drugs without worsening toxicity. Yet there is very little clinical evidence about the quality of life (QoL) after combination treatments, including HT, despite the fact that QoL has gained increasing importance in assessing the side effects of oncological therapies. In this retrospective study, the QoL of patients treated with HT in combination with radio(chemo)therapy (RCT) with curative or palliative intent was assessed by the EORTC QLQ-C30 questionnaire. The results of this analysis suggested that the combination of RCT and HT stabilizes or improves QoL for a clinically relevant time period after treatment. Hyperthermia (HT) in combination with radio(chemo)therapy (RCT) is a well-established cancer treatment strategy. This report analyses the quality of life (QoL), toxicity and survival outcomes in patients with different tumor entities who received HT in combination with RCT. The primary endpoint of this study was the assessment of QoL scale items 3 and 12 months after treatment in patients who were treated with palliative intent and curative intent, respectively. The secondary endpoints of this study were acute toxicities, 1-year overall survival (OS), and local progression-free survival (LPFS). Patients treated with curative intent experienced significant improvement in emotional functioning (EF), social functioning (SF), financial difficulties (FI) and insomnia (SL) 12 months after treatment. Patients had significantly improved FI and pain (PA) three months after palliative treatment. Acute toxicity of grade 3 or more was 26% during treatment and 4% after three months. The 1-year OS rates were 90% (95% CI: 79–96%) and 44% (95% CI: 31–59%) for patients treated with curative and palliative RCT combined with HT, respectively. Moreover, the 1-year LPFS rates were 94% (95% CI: 84–98%) for patients treated with curative intent and 64% (95% CI: 50–77%) for palliative patients. In summary, combined RCT and HT stabilized or improved QoL scale items for both curative and palliative indications. [ABSTRACT FROM AUTHOR]