Coral-like Ag-MoC/C-I and blocky Ag-MoC/C-II composites were obtained from one-step in situ calcination of [Ag(HL)(MoO)]·nHO [L: N-(pyridin-3-ylmethyl) pyridine-2-amine] under N/H and N atmospheres, respectively. The coral-like morphology of Ag-MoC/C-I is composed of interwoven nanorods embedded with small particles, and the nano-aggregate of Ag-MoC/C-II is formed by cross-linkage of irregular nanoparticles. The above composites are decorated on glassy carbon electrode (GCE) drop by drop to generate two enzyme-free electrochemical sensors (Ag-MoC/C/GCE) for amperometric detection of HO. In particular, the coral-like Ag-MoC/C-I/GCE sensor possesses rapid response (1.2 s), high sensitivity (466.2 μA·mM·cm), and low detection limit (25 nM) towards trace HO and has wide linear range (0.08 μM~4.67 mM) and good stability. All these sensing performances are superior to Ag-MoC/C-II/GCE, indicating that the calcining atmosphere has an important influence on microstructure and electrochemical properties. The excellent electrochemical HO sensing performance of Ag-MoC/C-I/GCE sensor is mainly attributed to the synergism of unique microstructure, platinum-like electron structure of MoC, strong interaction between Mo and Ag, as well as the increased active sites and conductivity caused by co-doped Ag and carbon. Furthermore, this sensor has been successfully applied to the detection of HO in human serum sample, contact lens solution, and commercial disinfector, demonstrating the potential in related fields of environment and biology. Graphical abstract.