Rational utilization of both adsorption and catalysis capabilities is an intriguing prospect in environmental remediation. Here, we demonstrate the tunability of these two capabilities in the case of bismuth selenide upon post-calcination. The temperature-related concentration of oxygen impurities in bismuth selenide gives a positive effect regarding charge separation. Meanwhile, the partial reservation of selenium is beneficial for the adsorption on antibiotics. Experimental results show that the bismuth selenide nanosheets calcinated under 180 °C exhibit the best photocatalytic performance, where the charge separation and adsorption reach an optimal equilibrium. The photocatalytic degradation efficiency reached over 90% within 120 min under simulated sunlight irradiation. The findings of this study highlight the regulation of adsorption and catalysis in environmental remediation, as well as providing new pathways to develop versatile nanomaterials for other environmental applications.