Background: The oncogenic gene E2F transcription factor 1 (E2F1) plays a key role in tumors. This study was designed to explore the effect of E2F1 gene expression manipulation and cisplatin on retinoblastoma cells and delineate the underlying mechanism. Methods: E2F1 expression in retinoblastoma cells was determined using quantitative real-time polymerase chain reaction (qRT-PCR). After E2F1 knockdown, cisplatin-treated cells presenting a malignant phenotype were identified through several methods, such as MTT assay, determination of half-maximal inhibitory concentration (IC50) values, flow cytometry, and comet assay. The effects of E2F1 silencing with/without cisplatin on downstream target genes were explored using qRT-PCR and Western blotting. To elucidate the mechanism involving E2F1 and centromere protein E (CENPE) in retinoblastoma, rescue experiments were conducted using cells overexpressing CENPE. Results: E2F1 was highly expressed in retinoblastoma cells (p < 0.05). E2F1 silencing improved the effectiveness of cisplatin in suppressing viability, as well as promoting apoptosis, increasing G1 phase and DNA damage of retinoblastoma cells (p < 0.05). Upregulation of CENPE expression partially reversed the effects of E2F1 silencing on cisplatin-treated cells (p < 0.05). Conclusion: E2F1 silencing enhances the effect of cisplatin in retinoblastoma by inhibiting CENPE.