PurposeThe controlling nutritional status (CONUT) score is an important tool for predicting the prognosis of colorectal cancer (CRC); however, its effectiveness is relatively insufficient. This study aimed to screen for more effective clinical indicators as supplements to the CONUT scoring system and improve the predictive value of CRC prognosis. Patients and methodsBetween 2014 and 2020, the clinical information of all CRC patients in our unit was retrospectively collected, and the CONUT scores were calculated based on the levels of serum albumin (ALB), lymphocytes (LC), and total cholesterol. The included patients were divided into the following three groups: normal nutrition (0–1), mild malnutrition (2–4), and moderate-to-severe malnutrition (5–12). The correlations between the CONUT score and baseline characteristics and clinical indicators were evaluated. ResultsThis study ultimately included 5014 CRC patients. The nutritional status of patients with colon cancer (CC) was worse than that of rectal cancer (RC). The nutritional status was worse in men than in women. The older the patient, the poorer the nutritional status, and the poorer the nutritional status, the longer the hospital stay. In addition, poor nutritional status in patients is indicated by higher values of neutrophils (NE), monocytes (MC), eosinophils (EOS), alkaline phosphatase (ALP), lactate dehydrogenase (LDH), carcinoembryogenic antigen (CEA), and lower values of white blood cells (WBC), basophils (BAS), haemoglobin (HB), total protein (TP), triglycerides (TG), low density lipoprotein (LDL), aspartate transaminase (AST), and blood urea nitrogen (BUN), which was statistically significant (P < 0.05). Indicators that significantly correlated with the CONUT score reflected the immune nutritional status, including WBC (odds ratio [OR] = 0.036, P < 0.001), NE (OR = 30.815, P < 0.001), MC (OR = 41.388, P < 0.001), EOS (OR = 27.577, P < 0.001), BAS (OR = 0.006, P = 0.046), and LDL (OR = 0.319, P < 0.001). ConclusionAdditional variables such as WBC, NE, MC, EOS, BAS, and LDL may be used as supplementary indicators in the CONUT scoring system to more effectively predict the clinical prognosis of CRC patients.