Frailty has been linked to unfavorable postoperative outcomes in patients with colorectal cancer (CRC). However, the prevalence of frailty among CRC surgery patients and its association with mortality and postoperative complications, as evaluated by the modified frailty index (mFI), have not been thoroughly investigated and necessitate clarification. PubMed, Web of Science, Embase, and CBM databases were systematically searched for relevant studies (up to January 2024), and the pooled prevalence and odds ratio (OR) estimate were calculated. A total of 16 studies containing 245 747 patients undergoing CRC surgery were included. The prevalence of frailty among CRC surgery patients was 31% (95% confidence interval [CI] = 20%–42%; I² = 100%, p < 0.001). In patients undergoing CRC surgery, frailty was associated with a higher incidence of postoperative complications (OR = 1.94; 95% CI = 1.47–2.56; I² = 91.9%, p < 0.001), but it did not exhibit any significant correlation with the 30-day mortality (OR = 5.17; 95% CI = 0.39–68.64; I² = 94.4%, p < 0.001). Frailty is common in CRC surgery and exerts a significant negative impact on the postoperative outcomes. Future research could explore the potential of the mFI to facilitate a more streamlined and precise quantification of frailty, thereby establishing a refined understanding of its correlation with surgery prognosis.