The MAL gene encodes Myelin and Lymphocyte Protein, mainly expressed in T cells with immunomodulatory effects, showing the potential as a target for immunotherapy. However, the mechanism of MAL in the regulation of immune infiltration and its association with the prognosis in pan-cancer patients remain elusive. We used the TCGA, TIMER2.0, GTEx, UCSC, and TISCH databases and the R programming tool to explore the role of MAL in cancers. MAL was differently expressed in the majority of malignancies relative to the matched healthy controls. Patients with low MAL levels had adverse survival outcomes in the BRCA and LUAD cohorts. In all cancer types, MAL showed a significant correlation to specific immune-subpopulation abundance in particular T cells as well as B cells. MAL was also implicated in immunological pathways in BRCA and LUAD, suggesting the important role of MAL in cancer immune regulation. In conclusion, the pan-cancer study indicates that MAL with excellent prognostic value is a potential immunotherapy target in multiple cancers.