Introduction <p> Solute carrier family 25 member 39 (SLC25A39) is crucial for regulating mitochondrial oxidative metabolism and homeostasis, linking to various physiological and pathological processes. Its expression landscape and mechanistic roles across cancer types remain largely unexplored. This study systematically profiled SLC25A39 in pan-cancer and assessed its prognostic relevance, molecular associations, and therapeutic potential.</p> Methods <p>Multi-omics database resources were utilized to perform an integrated analysis of SLC25A39, including its expression profiles, prognostic value, molecular mechanisms, and associations with the immune microenvironment across diverse tumors. The oncogenic role of SLC25A39 was confirmed through in vitro gene knockdown in hepatocellular carcinoma.</p> Results <p>SLC25A39 was predominantly over expressed in nearly all types of cancer. SLC25A39 serves as an unfavorable prognosis marker. Its expression was primarily linked to immune cell infiltration, the cancer immunity cycle, major histocompatibility complex, immune checkpoints, tumor mutation burden, microsatellite instability, and RNA modifications like m1A, m5C, m6A, as well as DNA methylation sites. Functional enrichment analysis reveals that SLC25A39 is commonly associated with immune-related pathways and cell cycle-related pathways in the pan-cancer dataset. Knockdown of SLC25A39 in Huh-7 and HepG2 cells significantly inhibited hepatocellular carcinoma cell proliferation.</p> Conclusions <p>SLC25A39 induces pro-tumorigenic effects across various cancer types. It serves as a potential biomarker.</p>