IntroductionThe role of postoperative radiotherapy in treating squamous cell carcinoma of the vulva remains controversial. This study evaluated the effect of radiotherapy on the survival of patients with postoperative squamous cell carcinoma of the vulva.MethodsClinical and prognostic information on patients diagnosed with vulvar squamous cell carcinoma from 2010 to 2015 was collected from the Surveillance, Epidemiology, and Prognosis (SEER) database. A propensity score matching (PSM) approach was used to balance the differences in clinicopathological characteristics between groups. The impact of postoperative radiotherapy on overall survival (OS) and disease-specific survival (DSS) was assessed.ResultsThe study included 3571 patients with squamous cell carcinoma of the vulva, of whom 732 (21.1%) received postoperative radiotherapy. After propensity score matching, multivariate analysis showed that age, race, N stage, and tumor size were independent influences on overall survival and disease-specific survival of patients. Postoperative radiotherapy did not improve patients’ overall survival or disease-specific survival. Further subgroup survival analysis showed that in patients with AJCC stage III, N1 stage, lymph node metastasis, and large tumor diameter (> 3.5 cm), postoperative radiotherapy resulted in a significant improvement in overall patient survival.ConclusionPostoperative radiotherapy is not indicated for all patients with postoperative vulvar cancer and has improved survival outcomes only for patients with AJCC stage III, N1, lymph node metastases and large tumor diameter (> 3.5 cm).Supplementary InformationThe online version contains supplementary material available at 10.1186/s12905-023-02522-w.