Noble metal nanoparticle-3D graphene hybrid nanocomposites possess the advantage of nanoparticles and graphene, which have attracted extensive interest. Here we developed a one-step laser induction method to prepare various noble metal nanoparticle-3D graphene nanocomposites. The nanocomposites were converted from polyimide film coated with the corresponding metal precursor-chitosan hydrogel ink. These nanoparticles including gold nanoparticles (AuNPs), silver nanoparticles (AgNPs), and platinum nanoparticles (PtNPs), were evenly distributed on the surface of porous 3D graphene. Furthermore, we prepared an AuNPs-3D graphene interdigitated array electrode using the one-step laser induction method, which was used to fabricate a flexible impedimetric immunosensor for the detection of Escherichia coli O157:H7. The immunosensor shows excellent performance including low detection limit, high selectivity, and great flexibility.