Purpose This study was performed to investigate the association of Glasgow prognostic score (GPS), combined positive score (CPS), and clinicopathological characteristics of locally advanced rectal cancer. Methods Between February 2012 and February 2018, 103 patients with locally advanced rectal cancer treated by neoadjuvant chemoradiotherapy and total mesorectal excision (TME) were retrospectively evaluated. Results According to the classification of the GPS, 85 (82.5%), 13 (12.6%), and 5 patients (4.9%) were classified as a score of 0, 1, and 2, respectively. Patients were classified into the GPS-low group (GPS of 0, n = 85) and GPS-high group (GPS of 1 or 2, n = 18) with an area under the curve of 0.582 for overall survival (OS). The mean programmed death-ligand 1 (PD-L1) CPS of the whole group was 2.24 (range, 0–70). The PD-L1 CPS of the GPS-high group was higher than the GPS-low group (P < 0.001). Multivariate analysis by Cox proportional hazards model indicated that GPS was associated with OS and disease-free survival (DFS). Furthermore, PD-L1 CPS was associated with DFS (hazard ratio, 1.050; 95% confidence interval, 1.017–1.083; P = 0.003). Conclusion Elevated GPS was related to the PD-L1 CPS. GPS and PD-L1 CPS were associated with the prognosis of locally advanced rectal cancer treated with neoadjuvant chemoradiotherapy followed by TME.