BACKGROUND: Adrenocortical carcinoma (ACC) is a rare endocrine neoplasia with poor prognosis. Emerging evidence suggests that kinesin family member 11 (KIF11) protein is overexpressed in several tumors and associated with the onset and progression of certain types of cancer; however, its biological functions and mechanisms in ACC progression have not been studied yet. Therefore, this study evaluated the clinical significance and therapeutic potential of the KIF11 protein in ACC. METHODS: The Cancer Genome Atlas (TCGA) database (n=79) and Genotype Tissue Expression (GTEx) database (n=128) were utilized to explore the expression of KIF11 in ACC and normal adrenal tissues. The TCGA datasets were then data mined and statistically analyzed. R survival analysis and univariate and multivariate Cox regression analyses were used to evaluate the effect of KIF11 expression on the survival rates, and a nomogram was used to predict its impact on prognosis. The clinical data from 30 ACC patients' from Xiangya Hospital were also analyzed. The effects of KIF11 on the proliferation and invasion of ACC NCI-H295R were further validated . RESULTS: Analytical data from the TCGA and GTEx databases showed that KIF11 expression was upregulated in ACC tissues and associated with T (primary tumor), and M (metastasis) and stages of tumor progression. Increased KIF11 expression was significantly associated with shorter overall survival, disease-specific survival, and progression-free intervals. Clinical data from Xiangya Hospital illustrated that increased KIF11 had a significantly positive correlation with shorter overall survival, T and pathological stages, and tumor recurrence risk. Monastrol, a specific inhibitor of KIF11, was further confirmed to significantly inhibit the proliferation and invasion of ACC NCI-H295R cell . The nomogram demonstrated KIF11 was an excellent predictive biomarker in patients with ACC. CONCLUSIONS: The findings demonstrate that KIF11 could be a predictor of poor prognosis and thus possibly serve as a novel therapeutic target for ACC.