Arginine, a nucleophilic amino acid crucial for protein structure and function, plays a key role in various biological processes like enzyme catalysis and macromolecular interactions. Despite challenges in selectively targeting its less reactive guanidine group, we developed a novel probe featuring phenyl glyoxal, AP-1, which exhibited exceptional chemical selectivity and reactivity towards arginines. Utilizing activity-based protein profiling (ABPP), we explored the human proteome across four cancer cell lines, quantifying about 17,000 arginines. This analysis led us to identify several previously unreported key hyperreactive arginines, including R43 of PKM, R171 of LDHA, R172 of LDHB, R341 of CKB, R168 of EIF4A1, and R118 of FUBP1, that play crucial roles in protein functions, highlighting the importance of these residues in mediating enzyme activity or macromolecular interactions and their therapeutic potential. Notably, mutation of CKB’s R341 can inhibit cell proliferation and migration via downregulating energy supply. Additionally, we introduced ArGO-LDHA-1, a covalent inhibitor targeting hyperreactive arginines of LDHA, demonstrating covalent binding properties and potential to enhance chemotherapy efficacy. This work not only validated the significance of numerous arginines with profound biological functions but also introduced a novel, efficient platform for large-scale arginine reactivity profiling.