: Colorectal cancer (CRC) poses a major global health challenge, with high incidence rates and ongoing treatment debates. Adjuvant chemotherapy benefits for high-risk subgroups, particularly stage II disease, remain controversial. This study seeks to clarify this issue by specifically examining the impact of adjuvant chemotherapy on disease-free survival (DFS) and overall survival (OS) in patients diagnosed with T4 colon cancer. : This retrospective study analyzed patients undergoing radical surgery for T4 colon cancer between 2002 and 2023. : Our study of 184 pT4 pN0 colon cancer patients revealed that 79.3% received adjuvant chemotherapy. Multivariate analysis demonstrated significant DFS improvement: a 60% reduction in risk for those who received adjuvant therapy (0.40 95% CI: 0.25-0.62, < 0.001). Lymphovascular invasion (LVI) and adjuvant treatment were also significantly associated with OS. Adjuvant treatment reduced mortality by 60% (HR: 0.40, 95% CI: 0.23-0.68, = 0.001). Patients with LVI had a 1.9-fold increase in mortality (HR: 1.94, 95% CI: 1.17-3.20, = 0.011). These findings underscore the potential value of adjuvant chemotherapy and highlight the importance of treatment completion in managing T4 colon cancer. : Our study identifies LVI and adjuvant chemotherapy as key prognostic factors in T4 colon cancer patients. These results support the consideration of adjuvant chemotherapy in this patient population.