Abstract: Titanium alloys are widely used in aerospace and related fields owing to their low density, high specific strength, and excellent corrosion resistance. To elucidate the effects of heat-treatment-induced microstructural evolution on the mechanical properties and corrosion behavior of Ti–6Al–4V alloy fabricated by laser powder bed fusion (L-PBF), three groups of specimens were prepared: as-built specimens, specimens subjected to stress-relief heat treatment at 650 ℃ for 4 h, and specimens subjected to annealing heat treatment at 800 ℃ for 2 h. Their microstructures, phase constituents, tensile properties, and electrochemical behavior were systematically investigated by microstructural characterization, X-ray diffraction (XRD), tensile testing, and electrochemical measurements. Owing to the rapid cooling inherent to the L-PBF process, the as-built specimens exhibited a predominantly α'-martensitic microstructure, resulting in a high ultimate tensile strength of 1260 MPa and a relatively low elongation of 13.06%, with a passive current density of 1.03×10^‒6 A·cm^‒2. After heat treatment at 650 ℃, the α′ martensitic partially decomposed, leading to the initial formation of an α+β dual-phase microstructure. The ultimate tensile strength decreased to 1141 MPa, while the elongation slightly increased to 13.51%. Meanwhile, the passive current density increased to 1.49×10^‒6 A·cm^‒2, indicating reduced corrosion resistance. Following heat treatment at 800 ℃, the α′ martensitic underwent further decomposition, accompanied by the formation of and α/β dual-phase microstructure. Consequently, the ultimate tensile strength decreased to 990 MPa, whereas the elongation increased to 17.51%. The passive current density decreased to 1.26×10^‒6 A·cm^‒2, indicating improved corrosion resistance compared with that of the specimens heat- treated at 650 ℃. These results demonstrate that annealing heat treatment enables comprehensive regulation of the strength, ductility, and corrosion resistance of L-PBF Ti–6Al–4V alloy by controlling α′-martensitic decomposition and the α/β phase transformation.