High risk HPV infection is a causative factor of cervical cancer. The constitutive expression of HPV E6-E7 genes is important for the maintenance of cancer phenotypes. The cellular transcription co-activator p300 plays a crucial role in the regulation of HPV genes thus it was targeted for the inhibition of HPV-associated cervical cancer. In the present study, HPV positive cervical cells were treated with C646, a selective inhibitor of p300, to investigate its influence on HPV E6-E7 expression and cancer cell growth. Results of RT-qPCR, Western-blot and promoter activity assays showed that C646 inhibited the transcription of HPV E6-E7, which was accompanied with the accumulation of p53 protein. Meanwhile, cell proliferation was suppressed, glucose metabolism was disrupted and apoptosis was induced via the intrinsic pathway. Generally, the anti-cervical cancer potential of C646 was demonstrated and a novel mechanism was proposed in this study.