This study developed an alkali-free accelerator containing nano-silica to enhance the early strength and durability of shotcrete concrete. Experimental results indicate that pre-dispersed nano-silica significantly reduced the viscosity of the accelerator, from 450 mPa·s to 305 mPa·s, and accelerated the hydration of cement. In terms of strength, the 1-day compressive strength increased from 12.5 MPa to 14.3 MPa, and the compressive strength at 56 days stabilized above 35 MPa. Furthermore, the accelerator with nano-silica not only improved the early strength of concrete but also enhanced its long-term stability and durability. Compared to the traditional external addition method, this approach uses less nano-silica and achieves better reinforcing effects, offering a high-performance, cost-effective solution for shotcrete.