Abstract: This review summarizes recent advances in neoadjuvant immunotherapy for advanced gastric cancer. Through literature search in PubMed, Web of Science, and CNKI databases from 2020 to 2023, we systematically analyzed the mechanisms, clinical applications, and biomarker research. Programmed death-1 (PD-1) inhibitors combined with chemotherapy significantly improve patient outcomes, while microsatellite instability (MSI), programmed death-ligand 1 (PD-L1) expression, and tumor mutational burden (TMB) have been identified as important predictive biomarkers. Multi-omics analysis shows great potential in identifying optimal responders, with pyroptosis-related gene scoring system (PRS) positively correlating with anti-tumor immune infiltration. Metabolic reprogramming and epigenetic regulation in the tumor microenvironment play key roles in immune evasion, while emerging targets such as Claudin 18.2 and combination targeting strategies further enhance therapeutic efficacy. Despite significant progress, precise patient selection and overcoming resistance mechanisms remain major challenges. Future research should focus on biomarker validation, personalized treatment strategy development, tumor microenvironment dynamic analysis, and novel combination therapy exploration to improve clinical outcomes.