<p>Kidney cancer has caused more than 150,000 deaths in 185 countries around the world and is a serious threat to human life. Clear cell renal cell carcinoma (ccRCC) is the most common type of kidney cancer. FDX1, a crucial gene for regulating copper death, plays an important role in tumors. However, its specific role in ccRCC remains unclear. In this study, by analysing data from the TCGA-KIRC and GEO databases and validation in clinical samples from our center, the expression characteristics of FDX1 and its relationship with tumor clinicopathological features and patient prognosis were clarified; the effects of FDX1 overexpression on ccRCC cell proliferation, apoptosis, migration, and invasion were determined via cell phenotype experiments and mouse orthotopic renal tumor growth models; and the downstream regulatory mechanism of FDX1 was determined via TMT proteomic sequencing, Co-IP assays, and RNA-sequencing detection. Our results confirmed that FDX1 was significantly underexpressed in ccRCC and that reduced FDX1 expression was associated with adverse clinicopathologic features and poor prognosis. FDX1 overexpression markedly inhibited the proliferation, migration, and invasion of ccRCC cells and promoted cell apoptosis in vitro. Mechanistically, FDX1 bound to the FMR1 protein and upregulated its expression, subsequently restraining Bcl-2 and N-cadherin expression and enhancing ALCAM, Cleaved Caspase-3, and E-cadherin expression. In mouse models, FDX1 overexpression significantly suppressed the growth and metastasis of renal tumors, but this inhibitory effect was markedly reversed after FMR1 expression was knocked down. Thus, our results confirmed that FDX1 expression is significantly reduced in ccRCC and serves as a prognostic marker for ccRCC patients and that its overexpression suppresses the growth and metastasis ability of ccRCC by promoting the expression of FRM1.</p>