This paper proposes a composite process for the fabrication ofMgB2 wire utilizing the excellent room temperature workability of Mg–Li alloy (LA141)as one of the promising processes for scale-up production. Starting compositeis a LA141 alloy tube filled with B powder or a mixture of B powder and SiCnanoparticles, which is sheathed with a pure Fe tube. The composite can be deformeduniformly into the final tape or wire with large cross-sectional area reductionand no intermediate annealing. During the subsequent heat treatment above themelting point of Mg–Li alloy, Mg in liquid state reacts with B to form a layer ofMgB2 single phase with dense structure. Li is little incorporated into theMgB2 phase and precipitates as Li compounds, forming a separate region from theMgB2 layer. Superconducting transition temperatureTc is 37–38 K and the highest transport critical current densityJc (core) obtainedso far is 7 × 103 A cm−2 at 4.2 K and 4 T.