Background: Several studies had been conducted on the association between blood group ABO and the risk of gastrointestinal malignancies, such as gastric and pancreatic cancer. Studies have also been conducted on the risk of obesity with colorectal carcinoma (CRC). It is unclear whether there is an association between blood group ABO and CRC and which group is more affected. Aim: The aim of this study was to show an association between the ABO blood group, Rh factor, and obesity with CRC. Patients and Methods: One hundred and two patients with CRC were included in our case–control study. Blood group, Rh factor, and BMI were estimated and compared with a control group of 180 Iraqis who came to the Endoscopy Department of Al-Kindy Teaching Hospital for preoperative control colonoscopy between January 2016 and January 2019. Results: The overall distributions of ABO and Rh factor were comparable between patients (41.17% A+, 5.88% A−, 6.86% B+, 2.94 B−, 1.96% AB+, 1.96% AB−, 37.25% O+, and 1.96% O−) and controls (26.66% A+, 1.11% A−, 20% B+, 1.11 B−, 13.3% AB+, 1.11% AB−, 34.44% O+, and 2.22% O−). Statistically, there were significant differences between patients with CRC and control subjects in terms of their blood groups. The A+ group was found in 42 cases (41.17%), followed by O+ in 38 cases (37.25%). Their BMI ranged from 18.5 to 40 kg/m2. Overweight patients were more common in 46 cases (45%) followed by obesity class І 32 cases (32.37%) with a P-value of 0.00016. Sixty-two of the patients with CRC (60.78%) were male and 40 cases (39.21%) were female. Their ages ranged from 30 to 79 years with a mean age of 55.49 years. CRC 37 cases occurred in the age group of 60–69 years (36.27). Conclusion: In this study, a statistically significant association was found between the occurrence of CRC and patients with blood group A+, O+, overweight, and obesity class І.