In this study, a method for electroless Ni–P plating with excellent adhesion via chemical wet etching to fabricate a Bi₂Te₃ thermoelectric module is proposed. The electroless Ni–P plating formed through the proposed process showed excellent adherence and did not desquamate, even under heat treatment at 200 °C for 24 h. Wet etching and electroless Ni–P plating was performed on a Bi₂Te₃ thermoelectric module, which showed excellent bond strength at approximately 10 MPa. The surface roughness of the Bi₂Te₃ thermoelectric element increased largely due to wet etching, and the adherence of the Ni–P plating could be secured by means of the anchor (surface roughness) effect.