Firstly, we found that HULC was remarkably overexpressed in both DLBCL tissues and cell lines. Moreover, we illustrated that HULC was closely related to DLBCL characteristics, such as Ann Arbor stages, B symptoms, CHOP-like treatment, rituximab and IPI. Importantly, we verified that HULC was an key predictive factor for DLBCL diagnosis and prognosis from sizable samples through the long time follow-ups. Furthermore, we reveal that the HULC knockdown could significantly arrest cell proliferation and induce apoptosis by repressing cyclin D1 and Bcl-2 in DLBCL cells.