The aim of this study was to investigate the relationship between marital status and disease outcome in patients with surgically treated colon cancer. Between June 2010 and December 2015, a total of 925 patients with newly diagnosed colon cancer receiving curative resection were enrolled. The effect of marital status on 5-year disease-specific survival (DSS) was calculated using Kaplan-Meier method, and was compared by log-rank tests. A Cox regression model was used to find significant independent variables and determine whether marriage had a survival benefit in patients with colon cancer, using stratified analysis. Among these patients, 749 (80.9%) were married, and 176 (19.1%) were unmarried, including 42 (4.5%) never-married, 42 (4.5%) divorced/separated, and 93 (10.1%) widowed. There was no significant difference between the married and unmarried groups in cancer stage or adjuvant treatment. Married patients had better 5-year DSS compared with unmarried patients (69.1% vs 55.9%, P < .001). Uni- and multivariate analyses also indicated that unmarried patients had worse 5-year DSS after adjusting for various confounders (adjusted HR [aHR], 1.66; 95% CI, 1.24-2.22). Further stratified analysis according to demographic variables revealed that unmarried status was a significant negative factor in patients with the following characteristics: age >65 years, female sex, well/moderately differentiated tumor, and advanced tumor-node-metastasis (TNM) stage disease (III-IV). Thus, marriage has a protective effect, and contributes to better survival in patients with surgically treated colon cancer. Additional social support for unmarried colon cancer patients may lead to improve outcomes.