Excessive CO₂ emissions cause global warming, while CO₂ interaction with crude oil can enhance oil recovery (EOR). To capture and reuse CO₂, nano-SiO₂ was cationically modified to synthesize nanoparticles (SCR₂). The structure and performance of SCR₂ were characterized by FT-IR, DLS, and TEM, confirming its excellent CO₂ adsorption capacity and surface activity. Compared with unmodified nano-silica, SCR₂ increased CO₂ adsorption capacity by 254.3% and reduced the core surface contact angle from 112.1° to 24.5°. Core flooding experiments showed that in low-permeability reservoirs, SCR₂ achieved a plugging rate of 87.5%, an enhanced oil recovery of 24.8%, and an ultimate oil recovery of 74.8% (23.8% higher than unmodified nano-silica). Mechanistically, SCR₂ plugs gas channeling pathways via its inherent nanoparticle properties and adsorption of dissolved CO₂ in the aqueous phase while improving rock surface wettability, thereby enhancing sweep efficiency and total oil recovery during CO₂ flooding. This study provides a promising approach for EOR and CO₂ resource utilization in low-permeability reservoirs.