Hydrogen peroxide (H2O2) sensing has many biomedical, healthcare and industrial applications. However, H2O2 sensors are limited in sensitivity and selectivity. Here, we investigate the application of magnetite (Fe3O4) coated gold nanorods (GNRs) of two aspect ratios as active glassy carbon electrode modifiers for the fabrication of H2O2 electrochemical sensors. We show that the GNR-Fe3O4 nanohybrids of a smaller aspect ratio (1.6) outperform the longer GNRs (aspect ratio 7.5) in the electrochemical detection of H2O2, as measured using cyclic voltammetry (CV) and amperometric techniques. The synthesized GNR-Fe3O4 in this study also demonstrated high sensitivity and selectivity, with performance surpassing previously reported H2O2 sensors.