Based on rst-principles calculations, several approaches such as defect engineering , doping/charging , and chemical functionalization have been proposed for combining ferroelectricity and magnetism in 2D materials. There are also a limited number of intrinsically multiferroelectric 2D materials discovered recently including the metal phosphorus chalcogenides family , buckled CrN and CrB 2 monolayers , and MXene Hf 2 VC 2 F 2 monolayer . Multiferroelectricity in monolayers of metal oxyhalides VOX 2 family[2630] has been predicted with interesting violation of the d 0 rule . In VOX 2 monolayers, the ferroelectric polarization direction is perpendicular to the partially occupied d xy orbital that is the origin of magnetism. That is why the partially occupied d orbital does not suppress the ferroelectric atomic displacement. Moreover, compared to ferroelectric TiOX 2 monolayer with empty d orbital, presence of an electron in d xy of VOX 2 monolayers rather positively contributes to the total electric polarization . Initially, ground state of VOI 2 monolayer was predicted as ferromagnetic and ferroelectric . However, later it has been predicted that ferroelectric VOI 2 monolayer can exhibit spiral magnetism with a short-period due to iodine's strong (compared to other halogens) spin-orbit coupling (SOC) . Alternatively, ferroelectricity in VOI 2 monolayer can also be suppressed by on-site strong Coulomb interaction making it ferromagnetic metal . The coexistence of ferroelectricity and ferromagnetism is predicted in VOF 2 monolayer , whereas VOCl 2 and VOBr 2 monolayers have ferroelectric ground state with antiferromagnetic (AFM) spin order . Note that VOCl 2 monolayer can be exfoliated experimentally from its bulk layered van der waals structure (space group: Immm) . Generally, ferroelectric materials exhibit good piezoelectricity. Although ferroelectricity and multiferroelectricity of MOX 2 monolayers have been investigated , their piezoelectric properties remain unknown to date. In this paper, we investigate piezoelectric properties of both TiOX 2 and VOX 2 monolayers also how the piezo-response change with magnetic order, which remain unexplored to date. We nd that these monolayers exhibits remarkably large piezo-response compared to most of the known 2D piezoelectrics.