A combination of casting and laser remelting was employed to develop a high-strength and heat-resistant Al−Si−Fe alloy suitable for powder bed fusion using a laser beam (PBF-LB). By clarifying the effects of the incorporated elements and their contents on the microstructure and mechanical performance of Al−Si−Fe alloys, the composition was optimized as Al−11Si−2.5Fe−2Mn−1.2Ni−0.4Cr (in wt.%). The optimized alloy was subsequently validated using PBF-LB, which exhibited favorable machinability, achieving a density of 99.8%. The room-temperature tensile strength of the PBF-LB manufactured Al−Si−Fe alloy reached (512.76±3.26) MPa, with a yield strength of (337.79±2.36) MPa and an elongation of (2.98±0.07)%. The enhanced room-temperature mechanical properties could be mainly attributed to the combined effects of fine-grain strengthening, solid solution strengthening, and precipitation strengthening. At 300 °C, the high-temperature tensile strength of the developed alloy reached (222.47±6.41) MPa, with a yield strength of (164.25±11.40) MPa and an elongation of (8.88±0.33)%, outperforming those of existing alloys documented in the literature. The improved high-temperature mechanical performance was primarily provided by the three-dimensional network comprising cellular heat-resistant Al₁₇(FeMnNiCr)₄Si₂ and α-Al(FeMn)Si phases.