In this paper, we report a new method for effective immobilization of Ag nanoparticles (AgNPs) decorated graphene oxide (AgNP/GO) composites onto thiolated single-stranded DNA decorated Au electrode (AuE) surface. The novel immobilization method is based on the coordination interactions and pi-pi stacking interactions between DNA bases and AgNP/GO composites. The morphologies of the AgNP/GO nanocomposites are characterized by transmission electron microscopy (TEM) and scanning electron microscopy (SEM). It is found that the AgNP/GO-decorated AuE exhibits remarkable catalytic performance for H2O2 reduction. This H2O2 sensor has a fast amperometric response time of less than 5 s. The linear range is estimated to be from 0.1 mM to 20 mM (r = 0.998) and the detection limit is estimated to be 1.9 mu M at a signal-to-noise ratio of 3, respectively.