Objective <p>This study aims to assess the therapeutic efficacy and safety of nivolumab combined with chemotherapy as a first-line treatment for advanced or metastatic gastric cancer, specifically comparing the outcomes of oxaliplatin-based versus albumin-bound paclitaxel (nab-paclitaxel)-based therapies.</p> Methods <p>We retrospectively analyzed 93 patients with advanced gastric cancer or gastroesophageal junction adenocarcinoma treated at the First Medical Center of Chinese PLA General Hospital from September 2017 to November 2022. Patients were categorized into the nivolumab + oxaliplatin (N-OX group) or nivolumab + nab-paclitaxel (N-AP group) based on the chemotherapy regimen. Progression-free survival (PFS), objective response rate (ORR), disease control rate (DCR), and safety were evaluated as endpoints.</p> Results <p>At the end of the follow-up period on September 31, 2023, we reported an ORR of 65.6% and DCR of 95.7% across all patients. The median PFS was 8.4&#xa0;months, with no significant difference between the N-OX and N-AP groups (median, 7.8 vs 9.5&#xa0;months; <i>P</i> = 0.450). Notably, patients with diffuse gastric cancer in N-AP group showed a 44.7% reduction in tumor progression risk compared with the N-OX group (<i>P</i> = 0.046). The overall safety profile was acceptable in two groups.</p> Conclusions <p>Our study suggested that nivolumab combined with chemotherapy was effective and safe as a first-line intervention for advanced gastric cancer. While both oxaliplatin and nab-paclitaxel regimens showed similar efficacy, the nab-paclitaxel may offer additional benefits for patients with diffuse gastric cancer. Further research is encouraged to confirm these findings and refine treatment strategies.</p>