Our previous miRNA profiling study indicated that microRNA-34c-3p (miR-34c-3p) was overexpressed and associated with survival in HCC. This study is aimed to confirm its clinical significance and explore the function and underlying mechanism of miR-34c-3p in HCC. We first evaluated miR-34c-3p expression and its relationship with prognosis in HCC patients. We then established stable HCC cell lines with miR-34c-3p overexpression and knockdown by the lentiviral packaging systems and performed the functional assays in vitro and in vivo, respectively. We next identified the target of miR-34c-3p by using microRNA target databases and dual-luciferase assay. Finally, the correlation between the expression of miR-34c-3p and the target gene was analyzed by immunohistochemistry and qRT-PCR in HCC tissues and hepatoma xenografts. Overexpressed miR-34c-3p was confirmed in HCC tissues and significantly associated with poor survival of HCC patients. miR-34c-3p expression was also recognized as an independent risk factor for DFS and OS in multivariate analysis. Ectopic expression of miR-34c-3p significantly promotes the proliferation, colony formation, invasion and cell cycle regression of HCC cell lines. Knockdown of miR-34c-3p remarkably blocked hepatoma growth in the xenograft model. miRNA target databases and luciferase reporter assay showed that NCKAP1 was a direct target of miR-34c-3p in HCC cells and the high expression of NCKAP1 in HCC tissues is significantly correlated with low expression of miR-34c-3p and associated with a favorable prognosis of HCC patients. The current study demonstrates that miR-34c-3p functions as a tumor promoter by targeting NCKAP1 that is associated with prognosis in HCC. miR-34c-3p and NCKAP1 may be new potential molecular targets for HCC therapy.