An effective diffusion barrier layer was coated onto the surface of BiTe-based materials to avoid the formation of brittle intermetallic compounds (IMCs) by the diffusion of the constituents of Sn-based solder alloys into the BiTe-based alloys. In this study, the electrochemical deposition of multi-layers, i.e., electroless nickel/electroless palladium/immersion gold (ENEPIG) was explored to enhance the bonding strength of BiTe materials with Cu electrodes. The thermoelectric modules with the ENEPIG plating layer exhibited high bonding strengths of 8.96 MPa and 7.28 MPa for the n- and p-type, respectively that increased slightly to 9.26 MPa and 7.76 MPa, respectively after the thermoelectric modules were heated at 200 °C for 200 h. These bonding strengths were significantly higher than that of the thermoelectric modules without a plating layer.