The study of χ3 borophene modification was considered finding an applicable technique to achieve more efficient approaches in CO₂ capturing. In the framework of density functional theory (DFT), two surface modification methods were described, external electric field or strain application on χ3 borophene, and the effect of them was investigated on CO₂ adsorption. All these methods affected the deformation charge density of the surface, which led to an increase in the CO₂ binding energy, in the studied range. The turning point in CO₂ capturing and structural changes appeared by applying an electric field of −0.030 a.u. strength with −0.48 eV adsorption energy. The uniaxial and biaxial compressive strain resulted in proper adsorption energy of −0.73 to −0.85 eV, although it caused a significant change in the planar structure of the surface. The structural and electronic properties, in addition to the charge density difference analysis, confirmed the chemisorption of CO₂ on modified surfaces. Lastly, for the first time, the response surface methodology in the DFT framework was used to evaluate the simultaneous effect of applying an external electric field and strain as well as charge injection on CO₂ adsorption. The generated quadratic equation predicts the CO₂ adsorption energy with high accuracy as a function of the modification parameters. This result would be very helpful in adjusting the modification parameters to achieve the desired CO₂ adsorption energy with lower experimental costs, where the χ3 surface is used for a special application such as CO₂ removal or sensing.