In this study, nanozeolite L is synthesized using an organic template-free system via hydrothermal approach. Its characterization shows that spherical nanoparticles with diameter in the range of 40–70 nm and high surface area are formed. After loading nanozeolite L with silver ions, it was mixed with carbon paste to prepare the modified electrode. The modified electrode was activated at an appropriate potential to convert Ag ions into Ag particles (Ag/LCPE) and its electrochemical properties were studied by cyclic voltammetry and amperometry methods. The results show that the constructed sensor has high catalytic activity and responds to H2O2 in a wide linear range with high sensitivity. The sensor had a low detection limit of 2 µM (S/N = 3) with a fast amperometric response time of 2 s. The high catalytic activity of proposed sensor results from the porous structure of nanozeolite L which provides high surface area for the formation of Ag active centers. Other features of the proposed sensor are high selectivity, stability, reproducibility, and repeatability. Also, the practical feasibility of the proposed sensor has been evaluated for the determination of H2O2 in human urine samples with good recoveries.