Cancerous inhibitor of PP2A (CIP2A) is an oncoprotein over-expressed and inversely associated with prognosis in lung and many other human cancers. It modulates phospho-Akt and stabilizes c-Myc, and is required for cell proliferation and malignant transformation, indicating that CIP2A may play an important role in carcinogenesis. We reported here that a small compound celastrol could induce a rapid degradation of CIP2A, through the ubiquitin-proteasome pathway with the carboxyl terminus of Hsp70-interacting protein (CHIP) as the E3 ligase. Celastrol directly bound with CIP2A protein, leading to promotion of CIP2A-CHIP interaction and subsequent degradation of CIP2A in non-small-cell lung cancer cells (NSCLC). Furthermore, celastrol effectively inhibited cell proliferation and induced apoptosis in NSCLC cells, while CIP2A silencing by specific siRNA enhanced these effects. Celastrol also suppressed tumor growth in xenograft murine models. In addition, celastrol potentiated the inhibitory effect of cytotoxic agent cisplatin on lung cancer cells in vitro and in vivo via inhibition of CIP2A-Akt pathway. These data indicate that celastrol is a CIP2A-targeting agent that may have therapeutic potentials in lung cancer.