Purpose <p>Sarcopenia is increasingly recognized as a risk factor for postoperative complications in gastrointestinal cancer surgery. This study aimed to assess the association between sarcopenia and postoperative complications following laparoscopic radical resection of non-metastatic colorectal cancer (CRC).</p> Methods <p>In this retrospective study, 387 non-metastatic CRC patients undergoing laparoscopic radical resection were categorized into a sarcopenic group and a non-sarcopenic group based on preoperative skeletal muscle index (SMI, cm²/m²). Logistic regression analysis was performed to identify independent predictors for postoperative complications.</p> Results <p>Sarcopenia was present in 156 (40.31%) patients. The incidence of postoperative complications was 32.3%, with a serious complication (Clavien-Dindo III–V) rate of 12.1%. Compared with non-sarcopenic patients, sarcopenic patients had significantly higher incidences of total complications (<i>P</i> &lt; 0.001) and severe complications (<i>P</i> = 0.026). Multivariable analysis identified sarcopenia as an independent risk factor for total postoperative complications (OR = 3.42, 95%CI 1.85–6.31). Further analysis of specific types of postoperative complications revealed that anastomotic leakage (<i>P</i> = 0.001), surgical site infection (<i>P</i> = 0.002), and surgical site adverse events (<i>P</i> = 0.001) rates were higher in sarcopenic patients. In multivariable analysis, sarcopenia was independently associated with anastomotic leakage (OR = 3.36, 95%CI = 1.12–10.12) and surgical site adverse events (OR = 3.02, 95%CI = 1.55–5.90).</p> Conclusions <p>Preoperative CT-derived sarcopenia can predict postoperative complications in patients with non-metastatic CRC undergoing laparoscopic radical resection, particularly anastomotic leakage and surgical site adverse events.</p>