Despite notable progress in wearable biosensors, continuous monitoring of therapeutic drugs in wound environments remains underexplored. Herein, we report the construction of atomic Se sites on polar CeO₂ (100) surfaces for the continuous antibiotic monitoring of complex wound exudates, using tetracycline as a model drug. Comprehensive characterization reveals a redox-mediated two-step selenization of CeO₂ (100) surfaces: (i) H₂SeO₃ reduces CeO₂ to Ce₂O₃, generating oxygen vacancies filled by SeO₃²⁻, and (ii) Ce₂O₃ is re-oxidized as SeO₃²⁻ is reduced, yielding stable Se–O–Ce motifs. These atomic-scale configurations restructure the pristine surface and induce spatially selective antifouling, wherein protein adsorption preferentially occurs on native Cesingle bondO domains while the Se–O–Ce regions remain electrochemically accessible. As a result, Se–CeO₂ retains ~45 % of its original response after 30-h continuous operation, compared to ~10 % for pristine CeO₂. Furthermore, the atomic Se sites offer dynamic flow responsiveness in a microfluidic wound model, exhibiting different lag times under varying perfusion rates. This behavior reflects individual variations in vascular perfusion and metabolism and demonstrates that atomic-scale surface engineering enables personalized pharmacokinetic monitoring in complex wound environments. This study pioneers the application of selenized ceria surfaces and opens new avenues for advanced biosensing and other biomedical applications.