Reduced graphene oxide-wrapped silver nanoparticles (Ag@rGO) were synthesized by a simple photochemical process with the GO nanosheets as both a stabilizing and reducing agent. The synthesized Ag@rGO nanohybrids were used as a localized surface plasmon resonance (LSPR) colorimetric sensor for the detection of chromium(VI) and carbaryl. For chromium(VI), the result showed a color change from yellow to colorless and linear-dependence of the absorption intensity on the concentration of Cr(VI) in the range 0.1–25 μM. For carbaryl, the calibration curve presented a high level of linearity in the range of 0.1–50 μM corresponding to color changes from yellow to purple. The limits of detection (LODs) for Cr(VI) and carbaryl were found to be 31 nM and 42 nM, respectively. The novel Ag@rGO nanohybrids will become an excellent platform for colorimetric probes in the detection of Cr(VI) ions and carbaryl or other heavy metal ions/pesticides.