A new highly selective chemosensor for Ag⁺ ions was designed and synthesized by covalently introducing well-known fluorophore 1,8-diaminonaphthalene (DAN) onto graphene oxide (GO) sheets. The resultant fluorescent sensor 1,8-diaminonaphthalene-graphene (GAP) was quenched due to the photoinduced electron transfer (PET) mechanism, and the intensity of second-order scattering (SOS) was enhanced upon addition of Ag⁺ ions. The fluorescent probe GAP exhibits no or a slight response to many other metal ions.