The role of adjuvant radiotherapy in the treatment of ampullary carcinoma (AC) remains unclear. We hypothesized that adjuvant radiotherapy (RT) does not improve survival following resection for AC. The SEER database was queried for patients with non-metastatic AC who underwent surgery (S) from 2004 to 2010. Propensity score (PS) modeling was applied to create balanced cohorts of patients that would be equally likely to receive RT. Cox proportional hazard models were used to compare survival. Of 1,287 patients, 329 (25.6%) received adjuvant RT. Unadjusted median overall survival (OS) for patients receiving adjuvant RT compared to S alone was 27 vs. 36 months (p = 0.14). Patients receiving RT were younger (63 vs. 69 years, p < 0.001), had more advanced tumors (69 vs. 53% T3/T4, p < 0.001), and had more frequent lymph node metastasis (73 vs. 40%, p < 0.001). Adjuvant RT failed to improve both overall survival (27 vs. 29 months, p = 0.58) and disease-specific survival (36 vs. 40 months, p = 0.92) in propensity-matched cohorts, although certain imbalances remained between treatment groups. Adjuvant RT does not confer a survival benefit for patients with ampullary tumors. The lack of disease-specific survival benefit suggests that it may also not be beneficial to prevent local recurrences.