Objectives: Systemic inflammatory response is strongly associated with poor oncological outcome in colorectal cancer (CRC). Perioperative inflammation caused by surgical stress can lead to the development of postoperative infectious complications (PIC) as well as cancer-related inflammation. We aimed to evaluate the prognostic potential of perioperative systemic inflammation by calculating the time-dependent cumulative C-reactive protein (CRP) levels during the perioperative period. Methods: We analyzed clinicopathological data from 540 patients with CRC who underwent potentially curative surgery at our institution. The time-dependent aggregated CRP level was denoted "cumulative CRP," which represents the area under the line of time (days) and the CRP levels preoperatively and on postoperative days 1, 3, and 7. Results: Cumulative CRP was significantly higher in patients with CRC undergoing open surgery than in patients undergoing laparoscopic surgery. In multivariate analysis, high cumulative CRP was an independent prognostic factor for disease-free survival (DFS) and overall survival (OS) in both the laparoscopic and open surgery groups. Patients with CRC and high cumulative CRP had significantly poorer DFS and OS than those with low cumulative CRP, including those patients without PIC. Conclusions: Cumulative CRP is an independent predictive marker of OS and DFS in patients with CRC who undergo curative surgery.