AgNPs have high electrocatalytic activity and sensitivity towards H2O2. Due to high surface energy, they tend to aggregate in the aqueous synthesis medium. The use of aggregated AgNPs in electrochemical sensing is undesirable as it reduces the sensitivity of the sensor. This was prevented by uniformly dispersing them in hydrophilic NH2-SBA-15 host and subsequently using as a glassy carbon electrode modifier for amperometric detection of H2O2 in aqueous solution. The current–time response of H2O2 reduction revealed that poor electrical conductivity of NH2-SBA-15 suppresses the cathodic current signals and sensitivity significantly. Therefore, electrode composition consisting of AgNPs impregnated NH2-SBA-15 was optimized, and a higher sensitivity of 171.3 μA cm−2 mM−1 with a wider linearity range (5.3–124.3 mM) was achieved. Thus, the sensor performance was higher than many other reported sensors, even those comprising of metal nanoparticles dispersed in electrically conducting hosts. Hence, a better performance of an enzyme-less electrochemical sensor can be achieved by a high loading of AgNPs in a hydrophilic host, which ensures their uniform dispersion, even if the host has a poor electrical conductivity. This work shows that a high loading of noble metal nanoparticles, with uniform dispersion in a hydrophilic host, can lead to a better performance of the H2O2 sensor, irrespective of conducting nature of the underlying host. This finding can also be useful for improving the performance of any enzyme-based sensor too, where analyte detection is based on formation of H2O2.