Two-dimensional (2D) ferromagnetic (FM) materials have been identified as the foundation for next-generation electronic devices. However, there are still rare materials that show intrinsic ferromagnetism, which makes searching for new ferromagnetic materials a very important task. In this work, we systematically investigate the electronic and magnetic properties of bilayer VI3 based on density functional theory (DFT). Our results show that bilayer VI3 shows a half-metallic characteristic. Furthermore, we observe a robust ferromagnetic ground state in bilayer VI3, which is independent of the stacking configurations. A model including intralayer through-bond and interlayer super-superexchange (SSE) effects is employed to analyze the mechanism of the ferromagnetic coupling. On account of the half-metallic character, an application as a spin valve is then explored using quantum transport simulations, which show 100% magnetoresistance. Our results provide guidelines for the application of the bilayer VI3 for the next-generation spintronic devices.