In this work, novel AlSi10Mg composites modified by SiC nanoparticles have been successfully produced by a combined route including solvent-assisted dispersion, low-energy planetary ball milling and selective laser melting. The effect of laser-energy-input (EV) on the microstructure evolution and mechanical properties of the composites was systematically studied. The results showed that the hardly dissolved or reacted SiC nanoparticles tended to be distributed at the cell boundaries, significantly refining the matrix grains by the promotion of heterogeneous nucleation process and the Zener pinning effect. However, the weak metallurgical bonding and the formation of Al4C3 phase caused a detrimental impact to tensile properties. On the contrary, the consumption of SiC nanoparticles at higher EV significantly enhanced the strength and elongation to fracture of the composites through the homogenization of microstructure, better metallurgical bonding, and the joint action of SiC/Al4SiC4/Al interface. Specifically, the AlSi10Mg/SiC composite prepared at 210 W presented excellent mechanical performance (131.7 HV0.1 for hardness, 101 GPa for modulus, and 440 MPa for strength) with a good ductility (7.4%).