Hydrogen peroxide (H2O2) is known as a key molecule in a variety of biological processes, as well as a crucial byproduct in many enzymatic reactions. Therefore, being able to selectively and sensitively detect H2O2 is not only important in monitoring, estimating, and decoding H2O2 relevant physiological pathways but also very helpful in developing enzymatic-based biosensors for other analytes of interest. Herein, we report a plasmonic probe for H2O2 based on 3-mercaptophenylboronic acid (3-MPBA) modified gold nanoparticles (AuNPs) which is coupled with surface-enhanced Raman scattering (SERS) to yield a limit of detection (LOD) of 70 nM. Our probe quantifies both exogenous and endogenous H2O2 levels in living cells and can further be coupled with glucose oxidase (GOx) to achieve quantitative and selective detection of glucose in artificial urine and human serum.