Renal cell carcinoma (RCC) is a heterogeneous disease. Identifying effective biomarkers is crucial for improving prognostic accuracy and therapy outcomes. This study investigates cell division cycle-associated 3 (CDCA3) as a novel biomarker for prognostic assessment and immunotherapy response in RCC. This study analyzed multi-omics data from The Cancer Genome Atlas (TCGA) for kidney renal clear cell carcinoma (KIRC), kidney renal papillary cell carcinoma (KIRP), and kidney chromophobe (KICH) subtypes to evaluate CDCA3 expression and its clinical implications. Functional enrichment and immune infiltration analyses were performed using bioinformatics tools gene set enrichment analysis (GSEA) and xCell. The prognostic value of CDCA3 was assessed through Cox regression and Kaplan-Meier survival analysis. Immunohistochemistry (IHC) was employed to confirm CDCA3 expression at the protein level in RCC samples. Higher CDCA3 expression correlated with poor survival outcomes and reduced response to programmed cell death protein 1 (PD-1) blockade therapies. Statistical analysis indicated that CDCA3 was an independent prognostic factor for poor survival in RCC. CDCA3 was consistently overexpressed in RCC tissues compared to normal tissues and was associated with adverse clinical features, including high Th2 cell infiltration and suppression of immune pathways. CDCA3 is a promising biomarker for RCC, offering insights into the tumor's prognosis and potential response to immunotherapy. The strong association between CDCA3 expression and poor therapeutic outcomes suggests that CDCA3 could be targeted in future therapeutic strategies.