Background <p>Hypoxia created an intratumoral oxygen gradient, promoting a more aggressive tumoral phenotype. Nevertheless, there was a lack of hypoxic panorama in gastric cancer (GC).</p> Methods <p>A total of 715 GC samples covering two independent cohorts were used for non-negative matrix factorization clustering and subtype exploration based on a tailored hypoxic signature. The prognosis, molecular markers, pathways, infiltrating of lymphocytes and stromal cells, and response of PD-1 therapy were compared between the subtypes.</p> Results <p>GC patients were divided into two groups, one indicted as normoxia, while the other defined as hypoxia. Hallmarks of aggressive tumor features such as EMT, angiogenesis, and KRAS signaling up were significantly enriched under hypoxic conditions and undoubtedly, worse outcome. Additionally, hypoxia confers GC with higher immune score, CAF infiltration, and resistant to pembrolizumab therapy in patients with metastatic GC (mGC).</p> Conclusions <p>Hypoxia-targeted or CAF-oriented therapy may overcome current chemoradiotherapy-resistant advanced GC but warrants further investigation.</p>