Updated publication reference for PubMed record(s): 31578252. Hydrogen peroxide (H2O2) is an important messenger molecule for diverse cellular processes. H2O2 oxidizes proteinaceous cysteinyl thiols to sulfenic acid, also known as S-sulfenylation, thereby affecting the protein conformation and functionality. Although many proteins have been identified as S-sulfenylation targets in plants, site-specific mapping and quantification remain largely unexplored. By means of peptide-centric chemoproteomics, 1,537 S-sulfenylated sites were mapped on more than 1,000 proteins in Arabidopsis thaliana cells. The H2O2 sensitivity was quantified of more than 70% of these endogenous oxidation events toward exogenous H2O2 stimulation. Proteins involved in RNA and metabolic processing were identified as hotspots for S-sulfenylation. Moreover, S-sulfenylation frequently occurred on cysteines located in catalytic sites of enzymes or on cysteines involved in metal binding, hinting at direct mode-of-actions for redox regulation. Comparison of human and Arabidopsis S-sulfenylation datasets provided 155 conserved S-sulfenylated cysteines, including Cys181 of the Arabidopsis MITOGEN-ACTIVATED PROTEIN KINASE4 (AtMAPK4) that corresponds to Cys161 in the human MAPK1, which is speculated to be a redox-regulatory site. Replacement of the noncatalytic Cys181 of the recombinant AtMAPK4 by the redox-insensitive serine decreased the protein kinase activity, emphasizing the importance of this noncatalytic cysteine. Altogether, we quantitatively mapped the S-sulfenylated cysteines in Arabidopsis plants under oxidative stress and delivered an unprecedented inventory for unraveling the precise role of these oxidized cysteines in plant redox signaling.