The adsorption of gas molecules (SO₂ and H₂S) on a hybrid of graphene oxide and tetrakis(4-carboxyphenyl)porphyrin (GO-TCPP) was studied via photoelectric conversion and protonation. π–π stacking interaction between TCPP and GO was employed to fabricate GO-TCPP film in a sodium dodecylbenzene sulfonate surfactant solution. A GO-TCPP  /  K⁺ exchanged glass optical waveguide sensor was prepared from the fabricated films, and the selectivity of the sensor was studied for volatile organic and acid gases. Results show that the sensor displayed good response to SO₂ and H₂S. Low-gas-concentration experiments detected SO₂ and H₂S concentrations of 1 and 100 ppb, respectively. Target gases were performed at different atmospheric humidities, indicating that humidity has little effect on the sensitivity of the components. Based on these results, the proposed SO₂ gas sensor has great potential for future applications in gas detection and related fields.