Background: Approximately 10% of colon cancer (CCa) develop peritoneal carcinomatosis. Studies have found that the administration of hyperthermic intraoperative chemotherapy (HIPEC) during cytoreductive surgery (CRS) can reduce the risk of recurrence and development of peritoneal carcinomatosis (PC). Additionally, intraoperative radiotherapy (IORT) has been shown to effectively treat and blunt neoplasm growth. However, no reports of the impact of concurrent HIPEC and IORT in CRS on CCa are available. Methods: We retrospectively reviewed the medical records of CCa patients with PC who received HIPEC and IORT during CRS. Demographics, treatment details, PC indexes (PCI), completeness of cytoreduction scores (CCS), and operative complications were recorded. Subsequently, overall survival (OS) was defined as the time period from surgery until death or loss of follow-up, and recurrence-free survival (RFS) was defined as the period from surgery until recurrence or loss of follow-up. Univariate hazard ratios (HR) were used to check for prognostic factors. Results: 17 CCa patients were included in our analysis. Patient characteristics are summarized in Table 1. The pT staging was T0 in 1 (5.9%), T3 in 6 (35.3%), T4a in 4 (23.5%), and T4b in 6 (35.3%). The pN staging was N0 8 (47.1%), N1a in 4 (23.5%), N1b in 2 (11.8%), N1c in 2 (11.8%), and N2b in 1 (5.9%). Finally, the pM staging was M0 in 8 (47.1%), M1a in 4 (23.5%), M1b in 2 (11.8%), and M1c in 3 (16.4%). PCI was ≤6 in 13 (76.5%) patients. The CCS was 0-1 in all, but two, patients. 1 patient had a positive resection margin. 8 (47.1%) received cisplatin with mitomycin C during HIPEC, followed by mitomycin alone (29.4%), reduced doses of cisplatin + mitomycin C (17.6%), and a reduced dose of mitomycin C alone (5.9%). Reduced dosage was due to old age in 3 and renal impairment in 1 patient. There were no intraoperative complications or HIPEC-related adverse effects. Two patients received two doses of IORT. 4 (23.5%) patients had postoperative complications, of which two complications were Clavein-Dindo grade 4a. Recurrence occurred in 8 (47.1%) patients, and 4 (23.5%) patients passed away. The median OS was not reached, and the RFS was 19 months. PCI > 6 (HR: 12.6, 95% CI: 1.6-256.8) and postoperative complication of grade 4 (HR: 8.6, 95% CI: 1-73) were associated with poor OS. Only PCI > 6 was associated with poor RFS (HR: 10.4, 95% CI: 1.7-80.8). Conclusions: Postoperative complications in HIPEC+IORT during CRS are comparable to other accepted treatments for CCa. Large, double-arm studies are needed to compare the effectiveness of this treatment.