DEAD-box helicase 21 (DDX21) is a conserved Asp-Glu-Ala-Asp (DEAD) box RNA helicase with multiple functions that is involved in various cellular processes and diseases. However, the role of DDX21 in the recurrence and prognosis of hepatocellular carcinoma (HCC) patients remains unknown. In the current study, we examined the protein expression of DDX21 in HCC tissues through immunohistochemical staining and analyzed the correlation between DDX21 protein expression and clinical outcome via Kaplan-Meier survival analysis. The Cox proportional hazards regression model was used to assess the interrelationships between the outcome and variable over time. Our results showed that increased expression of DDX21 protein was observed in HCC tissues compared with paracancerous tissues and was associated with advanced BCLC stage. Recurrent HCC patients had higher levels of DDX21 protein than nonrecurrent cases. Notably, DDX21 was an independent risk factor for predicting worse overall survival and recurrence-free survival in HCC patients. Furthermore, lack of DDX21 abated the growth and mobility of Hep3B cells. Taken together, our data highlight the clinical significance of DDX21 in the recurrence and prognosis of HCC patients and indicate that targeting DDX21 may represent an effective therapeutic strategy for the treatment of HCC.