The impact of selective laser melting (SLM) and direct aging (DA) heat treatment on the microstructure and mechanical properties of AlSi10Mg alloys was investigated. Microstructural characterization using SEM and EBSD revealed that SLM alloys exhibited a fine-grained cellular structure with α(Al) and Si-enriched phases, whereas cast alloys displayed a coarse eutectic Si morphology. Subsequent DA treatment demonstrated a 9.24% higher yield strength and a 5.56% improvement in ultimate tensile strength of the DA-B AlSi10Mg alloy when compared to the non-heat-treated alloy (NHT-AB), indicating significant improvements due to the DA process. Fracture surface analysis indicated predominantly ductile fracture in SLM alloys, contrasting with mixed ductile−brittle behavior in cast samples. Furthermore, EBSD texture analysis indicated a grain elongation in necked regions of SLM alloys after tensile deformation. The precipitation strengthening significantly contributes to the enhanced strength of the SLM alloys followed by the cell boundary strengthening. These findings highlight the potential of SLM and DA for producing high-performance AlSi10Mg components for aerospace, automotive, and rapid prototyping applications.