<p>This study investigates the influence of layer thickness on the microstructure, hardness, wear, and behavior of AlSi10Mg alloy fabricated by direct metal laser sintering (DMLS), comparing it with conventionally cast counterparts in both as-built and T6 heat-treated conditions. The 30-µm-layer thickness sample (AM 30) exhibited lower porosity and a finer microstructure than the 60-µm variant (AM 60). In the as-built DMLS samples, a continuous eutectic silicon network within the α-Al matrix transformed into discrete, spheroidized silicon particles after T6 treatment because of diffusion-driven coarsening. In contrast, the cast alloy displayed a coarse, flake-like silicon morphology, which also spheroidized upon heat treatment. The AM 30 sample had the highest hardness (130.2 VHN), while the AM 60 variant exhibited a hardness of 125.4 VHN, both higher than the untreated cast sample (65.9 VHN). Following heat treatment, hardness in the AM samples decreased (105.2 VHN for HT 30 and 99.2 VHN for HT 60), while the cast alloy’s hardness improved to 97.7 VHN because of Mg₂Si precipitation. Wear resistance, strongly linked to hardness and porosity, was lowest in the AM 30 sample, with a wear rate of 0.0000329 mm³/Nm, while AM 60 and Cast exhibited wear rates of 0.0000588 mm³/Nm and 0.000143 mm³/Nm, respectively. After heat treatment, the wear rates of HT 30, HT 60, and HT Cast were 0.0000626 mm³/Nm, 0.0000895 mm³/Nm, and 0.0000962 mm³/Nm, respectively. Abrasive wear predominated, with delamination and adhesive wear observed in samples with higher porosity. This study establishes that optimizing layer thickness in DMLS (particularly 30&#xa0;µm) significantly enhances wear resistance and mechanical performance of AlSi10Mg, even outperforming heat-treated cast counterparts, thereby highlighting the critical role of process parameters in tailoring additive-manufactured alloys.</p>