Cisplatin (CDDP) is a chemotherapeutic drug that is often used for the treatment of hepatoblastoma. However, many patients acquire resistance to therapeutic agents leading to local and distant treatment failure. It has been shown that suppression survivin contributed to the inhibition of tumor growth and enhanced chemotherapeutic sensitivity in several types of cancer. The aim of the present study was to determine whether treatment with sepantronium bromide (YM155), a novel small molecule inhibitor of survivin, enhanced the sensitivity of CDDP to hepatoblastoma cells, leading to the therapeutic efficacy of cisplatin. In vitro and in vivo models were used to examine the anticancer efficacy of YM155, either as a monotherapy or in combination with CDDP to identify more effective therapeutics against hepatoblastoma. The results showed that survivin expression was upregulated in hepatoblastoma tissues and cell lines, and that YM155 inhibited survivin expression in hepatoblastoma cells in a dose-dependent manner. YM155 enhanced sensitivity of CDDP to human HepG2 and HuH-6 hepatoblastoma cells. The YM155 combination with CDDP in hepatoblastoma cells significantly decreased cell proliferation and formation, and induced cell apoptosis than either agent alone. In a mouse xenograft model, YM155 combined with CDDP significantly suppressed tumor growth compared to the monotherapy. Taken together, these findings suggested that the combination of YM155 and CDDP is a promising drug candidate for the treatment of hepatoblastoma.