The primary benefit of using sulfites as a food additive is their antimicrobial and antioxidant properties, which stop fungi and bacteria from growing in a variety of foods. The application of analytical methods is necessary to ensure food quality control related to the presence of sulfites in a variety of foods. For the detection of sodium metabisulfite in food and urine samples, two sensors based on reduced graphene oxide doped with Pd paste and modified with 5,10,15,20-tetraphenyl-21H,23H-porphyrin and 5,10,15,20-tetrakis (pentafluorophenyl chloride)-21H,23H-iron (III) porphyrin were proposed. The new sensors were evaluated and characterized using square wave voltammetry. The response characteristics showed that the detection limits for the sensors were 3.0 × 10−12 mol L−1 for TPP/rGO@Pd0 based sensors and 3.0 × 10−11 mol L−1 for Fe(TPFPP)Cl/rGO@Pd0 based sensors while the quantification limits were 1.0 × 10−11 mol L−1 for TPP/rGO@Pd0 based sensors and 1.0 × 10−10 mol L−1 for Fe(TPFPP)Cl/rGO@Pd0 based sensors. The sensors can be used to determine sodium metabisulfite in a concentration range between 1.0 × 10−11 and 1.0 × 10−7 mol L−1 for TPP/rGO@Pd0 based sensors and between 1.0 × 10−10 mol L−1 and 1.0 × 10−6 mol L−1 for Fe(TPFPP)Cl/rGO@Pd0 based sensors. A comparison between the proposed methods’ results and other analytical applications is also presented.