Fabric electrodes are an important part of long-term medical-health-monitoring garments, but sweat corrosion can greatly affect their longevity and stability. In this study, the metal fabric biopotential sensor was chemically modified with 3-mercaptopropyltrimethoxysilane (MPTS). Ag/AgCl was formed on the electrode surface by constant voltage deposition. Ag/AgCl/3-Mercaptopropyltrimethoxysilane/silver-plated nylon electrodes (Ag/AgCl/MPTS/SPNE), Ag/AgCl/3-mercaptopropyltrimethoxysilane/silver-plated copper wire electrodes (Ag/AgCl/MPTS/SPCWE), and Ag/AgCl/3-mercaptopropyltrimethoxysilane/sterling silver yarn electrodes (Ag/AgCl/MPTS/SSYE) were prepared. Molecular dynamics (MD) simulations using Forcite were performed to investigate the anticorrosion mechanism of MPTS. The effects of the MPTS dip-coating time and chlorination parameters on the electrochemical properties were investigated. The corrosion resistance of the biopotential sensor was tested in simulated sweat and NaCl solutions. We analyzed the suitability of the biopotential sensor by the softness test, abrasion resistance test, washing resistance test, and motion noise resistance test. Ag/AgCl/MPTS/SSYE provides optimal corrosion resistance, comfort, motion noise resistance, and electrical properties. It can be used for wearable applications such as long-term electrocardiogram (ECG) signals, electromyogram (EMG) signals, and neuromuscular electrical stimulation (NMES).