BACKGROUND: For unresectable or metastatic gastric/gastroesophageal junction cancer (G/GEJC), immune checkpoint inhibitors (ICIs) plus platinum-based doublet chemotherapy [FOLFOX (leucovorin, fluorouracil, and oxaliplatin) and XELOX (capecitabine and oxaliplatin)] are currently recommended as the standard first-line treatment. Research indicates that ICIs combined with paclitaxel have a synergistic effect, but the evidence is insufficient. This multicenter, retrospective study aimed to compare the efficacy and tolerability of ICIs [mainly anti-programmed cell death-1 (anti-PD-1) antibodies] plus a paclitaxel-based chemotherapy regimen (ICIs plus PTX) METHODS: This research involved 123 patients with advanced G/GEJC at three institutions in China from August 2019 to June 2022. The ICIs plus PTX group included 58 patients, whereas the ICIs plus OXA group included 65 patients. We compared the efficacy and safety of two treatment regimens. RESULTS: Fifty-eight patients (47.2%) received ICIs plus PTX, and 65 patients (52.8%) received ICIs plus OXA. The median progression-free survival (PFS) [8.07 CONCLUSIONS: In summary, ICIs plus PTX are as effective as ICIs plus OXA for treating advanced G/GEJC with manageable toxicity. The advantages of ICIs plus PTX in terms of adverse events (AEs) may support it as an alternative to ICIs plus OXA.