Background <p>The immunometabolic enzyme Interleukin-4-induced-1 (IL4I1) is implicated in cancer pathogenesis, yet its specific function and clinical relevance in acute myeloid leukemia (AML) remain unclear.</p> Methods <p>Comparative analysis of <i>IL4I1</i> mRNA levels between AML patients and normal controls was performed using the Cancer Genome Atlas (TCGA) and Genotype-Tissue Expression (GTEx) databases. The Kaplan–Meier survival analysis was conducted to evaluate the prognostic value of <i>IL4I1</i>. Functional insights were derived from analyses of differentially expressed genes (DEGs), Gene Set Enrichment Analysis (GSEA), and Gene Ontology (GO)/Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment. Immune infiltration was evaluated using the ssGSEA, ESTIMATE, quanTIseq and single-cell RNA sequencing (scRNA-seq) analysis. Finally, in vitro and in vivo functional experiments were perfromed to explore the impact of IL4I1 on AML progression and immunoregulation.</p> Results <p><i>IL4I1</i> expression was significantly elevated in AML compared to normal controls (<i>p</i> = 0.0004) and associated with poorer overall survival (<i>p</i> = 0.003). Bioinformatic analysis revealed that IL4I1 was linked to immune-related pathways—including humoral immune response, leukocyte interactions, and chemokine signaling—and to cellular amino acid metabolism. Its expression correlated with immune cell infiltration and checkpoint molecule expression. Experimentally, IL4I1 promoted leukemia cell proliferation in vitro and in vivo (<i>p</i> &lt; 0.05). Furthermore, silencing <i>IL4I1</i> suppressed M2 macrophage polarization and reduced secretion of inflammatory factors (<i>p</i> &lt; 0.05).</p> Conclusions <p><i>IL4I1</i> may serve as a potential biomarker for poor prognosis and an attractive target for immune-based therapeutic interventions in AML.</p>