Nanomagnet-silica shell (FeO@SiO) decorated with Au@Pd nanoparticles (NPs) were synthesized successfully. The characterization of FeO@SiO-NH-Au@PdNPs was achieved using several spectroscopic and microscopic techniques. The quantitative surface analysis was confirmed using X-ray photoelectron spectroscopy. The FeO@SiO-NH-Au@PdNPs exhibited excellent peroxidase-like activity by effectively catalyzing the oxidation of 3,3',5,5'-tetramethylbenzidine (TMB) in the presence of HO. The absorption peaks at 370 and 652 nm confirmed the peroxidase-like activity of the FeO@SiO-NH-Au@PdNPs. The Michaelis-Menten constant () of 0.350 and 0.090 mM showed strong affinity toward HO and TMB at FeO@SiO-NH-Au@PdNPs. The mechanism of the peroxidase-like activity was found to proceed via an electron transfer process. A simple colorimetric sensor based on glucose oxidase and FeO@SiO-NH-Au@PdNPs showed excellent selectivity and sensitivity towards the detection of glucose. The fabricated glucose biosensor exhibited a wide linear response toward glucose from 0.010 to 60.0 μM with an limit of detection of 60.0 nM and limit of quantification of 200 nM. The colorimetric biosensor based on FeO@SiO-NH-Au@PdNPs as a peroxidase mimic was also successfully applied for the determination of glucose concentrations in serum samples. The synthesized FeO@SiO-NH-Au@PdNPs nanozymes exhibited excellent potential as an alternative to horseradish peroxidase for low-cost glucose monitoring.