Nanofluids have shown great potential in enhanced oil recovery (EOR) by reducing interfacial tension (IFT) and altering wettability. However, their impact on reservoir geomechanics—stress redistribution, pore pressure, and rock deformation—has received limited attention. This review systematically examines nanofluid-assisted EOR from an integrated physicochemical and geomechanical perspective, covering research from 2007 to 2025. Key nanoparticles (silica, alumina, carbon-based) and preparation methods (single-step vs. two-step) are analyzed in terms of their effects on porosity, permeability, compressibility, and fracture stability. Unlike previous reviews that focus solely on EOR mechanisms, this work presents a systematic integration of nanofluid behavior with reservoir geomechanics. The novelty lies in bridging these two domains to establish a framework for designing mechanically stable EOR operations. Critical knowledge gaps are identified, including long-term nanoparticle (NPs) stability, field-scale geomechanical data, and coupled hydro-mechanical modeling needs. Overall, this review provides actionable insights for sustainable and reservoir-integrity-aware nanofluid applications in the petroleum industry.