Abstract Cisplatin-based chemotherapy constitutes the cornerstone of first-line treatment for muscle-invasive and metastatic bladder cancer (BCa); however, the frequent emergence of chemoresistance presents a formidable clinical obstacle. In the present study, by combining a systematic CRISPR-Cas9 E3 ligase library screen with drug sensitivity data from the GDSC database, DCST1 (DC-STAMP Domain Containing 1) was identified as a pivotal driver of cisplatin resistance.