Background and Objectives: This study aimed to investigate the potential risk factors for severe postoperative complications after oncologic right colectomy. Materials and Methods: All consecutive patients with right colon cancer who underwent right colectomy in our department between 2016 and 2021 were retrospectively included in this study. The Clavien–Dindo grading system was used to evaluate postoperative complications. Univariate and multivariate logistic regression analyses were used to investigate risk factors for postoperative severe complications. Results: Of the 144 patients, there were 69 males and 75 females, with a median age of 69 (IQR 60–78). Postoperative morbidity and mortality rates were 41.7% (60 patients) and 11.1% (16 patients), respectively. The anastomotic leak rate was 5.3% (7 patients). Severe postoperative complications (Clavien–Dindo grades III–V) were present in 20 patients (13.9%). Univariate analysis showed the following as risk factors for postoperative severe complications: Charlson score, lack of mechanical bowel preparation, level of preoperative proteins, blood transfusions, and degree of urgency (elective/emergency right colectomy). In the logistic binary regression, the Charlson score (OR = 1.931, 95% CI = 1.077–3.463, p = 0.025) and preoperative protein level (OR = 0.049, 95% CI = 0.006–0.433, p = 0.007) were found to be independent risk factors for postoperative severe complications. Conclusions: Severe complications after oncologic right colectomy are associated with a low preoperative protein level and a higher Charlson comorbidity index.