Background/Objectives: Endometrial cancer is one of the most common malignancies of the female reproductive system. Fortunately, risk-adapted therapy offers a promising chance of recovery, even from locally advanced disease. In particular, older patients with higher risk factors benefit markedly from adjuvant radiotherapy with or without chemotherapy. Nevertheless, this also carries a risk of higher cumulative toxicity thereafter. Although this phenomenon has been observed in older patients, it has not yet been adequately evaluated. Methods: This retrospective study compared the clinical features of patients receiving adjuvant radiotherapy with or without sequential chemotherapy or radiotherapy with concomitant chemotherapy between 2011 and 2023. The cohort was divided into two groups: patients over 65 years old and those under 65. Results: 100 patients received adjuvant radiotherapy at our center between 2011 and 2023. The mean age of patients was 66.87 years. We observed that neither diabetes, obesity, concurrent, sequential chemotherapy, nor para-aortic field irradiation was associated with an increased incidence of acute radiogenic side effects such as cystitis, diarrhea, proctitis, radiodermatitis, nausea, or vaginal dryness according to CTCAE ≥ 2 (all p > 0.50). No difference was found between the two groups in terms of the incidence of radiotherapy-associated toxicity. Conclusions: We found no increase in toxicity in elderly patients after adjuvant radiotherapy with or without chemotherapy.