This work presents the development of a quinoxaline and rhodamine conjugate system that acts as a colorimetric chemosensor for hydrogen sulfate (HSO4−) ions in methanol media. This sensor has been characterized both theoretically and experimentally. The detection limits for HSO4− are small as 0.71 µM and 3.8 µM for the absorption and emission experiments, respectively. The effectiveness of the probe in recognizing HSO4− both in gel and solid phase is evaluated as well. Thus, this works presents a simple strategy to detect the environmental HSO4− pollutant event at tiny concentrations.