Platinum (Pt)-based chemotherapeutics are widely used for cancer treatment in clinical trials. It has been reported that protein O-linked β--acetylglucosamine (O-GlcNAc) modification occurs on several important proteins implicated in regulating cancer cell response to Pt drugs. However, the O-GlcNAc proteomic landscape during this process remains poorly characterized. Herein, we report quantitative profiling of O-GlcNAcylation sites with carboplatin exposure, by using a chemoenzymatic labeling-assisted chemoproteomic approach. A total of 244 O-GlcNAcylated sites, many of which occur on essential genome stability regulators, are quantified. Furthermore, we discover that the cellular O-GlcNAc level is elevated upon carboplatin treatment and suppression of O-GlcNAcylation renders cancer cells more sensitive to carboplatin. These results establish a valuable resource for elucidating the functional role of O-GlcNAcylation in carboplatin response and suggest potential insights into cancer chemotherapy. The chemoproteomic strategy should be generally applicable for monitoring O-GlcNAc dynamic changes in various pharmacological processes.