We reported the direct electrochemical hydrogen peroxide detection on three-dimensionally ordered macroporous SmCoO₃ (3DOM-SmCoO₃) perovskite oxide electrode synthesized via a poly (methyl methacrylate) (PMMA) colloidal crystal templating route. The low-cost and simple 3DOM-SmCoO₃ sensor not only overcome the various disadvantages of enzyme- and noble metal-based sensors but also display a superior sensing performance for H₂O₂ detection. More importantly, using 800 nm PMMA microspheres, a hexagonally ordered macroporous crystalline structure can be created, which features large surface area (20.14 m² g⁻¹) and large, open, interconnected channels for facile reactants and ions diffusions. The resultant 3DOM-SmCoO₃ synthesized using 800 nm PMMA microspheres template (3D-SC-800) displayed higher sensitivity (715 and 460 μA mM⁻¹ cm⁻²), lower limit of detection (0.004 μM), larger detection linear range (0.1–10,000 μM), and higher selectivity in the presence of interfering species (i.e., glucose, ascorbic acid, dopamine, and uric acid), for H₂O₂ detection, relative to SmCoO₃ (SC) and SmCoO₃ synthesized using 200 nm PMMA template (3D-SC-200). Our comprehensive electrochemical characterization attributes the superior H₂O₂ electrooxidation performance of 3D-SC-800 to its fast electron transfer kinetics and diffusion rate. What we demonstrated here bolsters the future opportunity to harness ordered macroporous perovskite oxide-based materials for highly active and selective non-enzymatic H₂O₂ detection.