Electro-codeposition of nano-sized SiO₂ particles into the metal matrix in aqueous solution is generally difficult. In this paper, the nano-sized SiO₂ particles were successfully codeposited in the Ni matrix from a choline chloride (ChCl)/ethylene glycol (EG) based deep eutectic solvent (DES) by pulse electro-codeposition. The effects of nano-sized SiO₂ particles on electrochemical behaviour of Ni(II) were investigated. The microstructure, composition and corrosion resistance of pure Ni and Ni-SiO₂ nanocomposite coatings were explored. Results showed that the SiO₂ nanoparticles exhibited excellent dispersion stability in ChCl:2EG DES without any stabilizing additives and the presence of SiO₂ nanoparticles have significant effects on the nucleation mechanism of Ni. The maximum content of SiO₂ nanoparticles in composite coatings can achieve 4.69 wt.%, which closes to the level of co-deposition micro-sized SiO₂ particles from aqueous solution. The Ni-SiO₂ nanocomposite coatings exhibit much better corrosion resistance than pure Ni coating, and the corrosion resistance performance increases with increasing SiO₂ content in the composite coatings.