Urothelial carcinoma (UC) is characterized by a high incidence ofTP53mutation, and overcoming resistance to cisplatin-based chemotherapy in UC is a major concern. Wee1 is a G2/M phase regulator that controls the DNA damage response to chemotherapy inTP53-mutant cancers. The combination of Wee1 blockade with cisplatin has shown synergistic efficacy in several types of cancers, but little is known regarding UC. The antitumor efficacy of the Wee1 inhibitor (AZD-1775) alone or in combination with cisplatin was evaluated in UC cell lines and a xenograft mouse model. AZD-1775 enhanced the anticancer activity of cisplatin by increasing cellular apoptosis. AZD-1775 inhibited the G2/M checkpoint, improving the sensitivity of mutantTP53UC cells to cisplatin by enhancing the DNA damage process. We confirmed that AZD-1775 combined with cisplatin reduced tumor volume and proliferation activity and increased the markers of cell apoptosis and DNA damage in the mouse xenograft model. In summary, the Wee1 inhibitor AZD-1775 combined with cisplatin elicited a promising anticancer efficacy in UC, and constitutes an innovative and promising therapeutic strategy.