Aluminum alloy 2024 provides high mechanical properties and good machinability for high-performance applications. However, the poor castability of the high-performance alloy makes it impractical to produce complex structures by economical casting processes. Here, a small fraction of TiC nanoparticles are dispersed into aluminum alloy 2024 melt for nano-treating, which improves the fluidity of aluminum alloy 2024, while eliminating hot cracking and enhancing the surface quality of the casting. Further study reveals that nanoparticles induce effects such as releasing latent heat slowly, restricting grain growth, and enhancing wettability. The results demonstrate the potential of the emerging nano-treating technology in making traditionally uncastable alloys viable for low-cost casting operations to deliver products with enhanced high performance for numerous applications.