BackgroundDisparities in gastric cancer (GC) outcomes show a higher disease burden among minorities. We aimed to evaluate the associations between sociodemographic and system‐level factors and guideline‐concordant treatment among GC patients.MethodsCohort study with GC patients in the National Cancer Data Base (2006–2018) treated with upfront resection or neoadjuvant therapy (NAT). We used logistic regression to identify associations between deviations from guideline‐concordant therapy and patient‐ and system‐level factors, and Cox regression models to assess risk of death.ResultsThe cohort included 43 597 GC patients treated with endoscopic resection (8.9%), surgery only (47.1%), surgery and adjuvant therapy (20.6%), or NAT followed by surgery (23.5%). A total of 31 470 patients (72.2%) received guideline‐concordant therapy. Relative to Non‐Hispanic Whites (NHWs), Non‐Hispanic Blacks (NHBs) (odds ratio [OR] 1.19, [95% confidence intervals 1.10–1.28]) and Asian/Pacific Islanders (APIs) (OR 1.12 [1.03–1.23]) had an increased risk of deviations from treatment guidelines. Medicare/Medicaid increased the risk of deviations while treatment at high‐volume facilities decreased its risk for all races/ethnicities. Deviations from guidelines were associated with an increased risk of death (hazard ratio 1.56 [1.50–1.63].ConclusionsRacial disparities in the delivery of guideline‐concordant therapy among GC patients are affected by several sociodemographic factors at the patient‐ and system‐level.