Objective This study aimed to compare the effectiveness of adjuvant chemoradiotherapy (CRT) and adjuvant chemotherapy (ChT) for T3–4/N+ gastric cancer (GC) following D2/R0 dissection, and identify the specific subgroups that could benefit from adjuvant CRT.Methods All eligible patients were divided into the CRT group and ChT group. We assessed the survival outcomes and patts of recurrence for each group, and determined the prognostic factors for survival by performing Cox proportional risk regression analyses. Results A total of 192 gastric cancer patients were included in the study. The estimated 3-year and 5-year disease-free survival (DFS) probabilities in the CRT and ChT groups were 52.9％ vs. 36.7％ (P = 0.024) and 41.2％ vs. 31.1％ (P = 0.148), respectively, and the estimated 3-year and 5-year overall survival (OS) probabilities were 82.4％ vs. 70.0％ (P = 0.044) and 52.0％ vs. 35.6％ (P = 0.022). Patients in the CRT group had a lower risk of locoregional recurrence than those in the ChT group (20.6％ vs. 34.4％; P = 0.031). The subset analyses revealed that patients with stage N1–2 disease were more likely to benefit from adjuvant CRT than from adjuvant ChT (DFS: 53.1％ vs. 36.4％; P = 0.039; OS: 53.1％ vs. 38.6％; P = 0.036). Conclusion For locally advanced gastric cancer patients with LN+, adjuvant CRT showed superior survival benefits compared with adjuvant ChT alone. Patients with N1–2 achieved better survival from adjuvant CRT.