Abstract <p>A method is developed for immobilizing a binary gold–palladium (Au–Pd) system on the surface of a glassy carbon (GC) electrode coated with reduced graphene oxide (rGO). Using rGO as a matrix for the inclusion of the Au–Pd binary system significantly enhanced its catalytic activity for the electrooxidation of tetracycline. This improvement is attributed to an increased dispersity of the deposit and the formation of metal nanoparticles in the nanometer range, with an average particle size of 50 nm. The optimal conditions for immobilizing the Au–Pd binary system were identified to maximize the electrocatalytic effect. The feasibility of the amperometric detection of tetracycline on the GC electrode modified with the Au–Pd and rGO composite was demonstrated under flow-injection analysis conditions. The proposed method exhibits high sensitivity (with a detection limit of 5 nM), rapidity, and high throughput (60 samples/h). The developed flow-injection amperometric method for tetracycline determination was successfully applied to analyze flower honey samples from different regions of the Volga area.</p>