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Background Glucose restriction is a hallmark of the tumor microenvironment (TME), yet how tumor cells adapt to this metabolic stress and the impact of metabolic reprogramming on the TME remains incompletely understood.Methods A genome-wide CRISPR knockout positive screen was performed to identify key mediators of cellular adaptation to glucose restriction. Using biochemistry, molecular biology, metabolomics and confocal immunofluorescent microscopy to elucidate the underlying molecular mechanisms. Additionally, single-cell RNA sequencing and orthotopic tumor models were used to characterize TME remodeling and assess therapeutic efficacy.Results We identified zinc and ring finger 3 (ZNRF3) as a key mediator of cellular adaptation to glucose restriction through genome-wide CRISPR/Cas9 screening. Multiple tumor cells adaptively survived in glucose-restricted conditions with downregulated ZNRF3. Mechanistically, low glucose suppresses ZNRF3 expression, leading to Wnt pathway activation and subsequent transcriptional repression of stearoyl-CoA desaturase (SCD). This metabolic rewiring enhances antitumor immunity by increasing T-cell infiltration and cytotoxicity. In multiple preclinical models, dietary glucose restriction synergizes with immune checkpoint blockade to suppress tumor growth.Conclusion These findings establish the ZNRF3-Wnt-SCD axis as a metabolic checkpoint controlling tumor cell fate under glucose restriction and provide a rationale for combining dietary intervention with immunotherapy.