Objective: The effect of incorporating various concentrations of 210 nm ZnO nanoparticles (ZnO-NPs) into resin-based composites (RBCs) and glass-ionomer cement (GIC) on their color and surface roughness after immersion in red wine is evaluated. Materials and Methods: 12 experimental groups (n = 12) were tested, including three commercial restorative materials: a microhybrid RBC (Gradia Direct^®), a nanohybrid RBC (Evetric^®) and a GIC (Fuji IX^®). These were modified with ZnO-NPs at weight concentrations of 1%, 2%, and 3%. Color coordinates (L*,a*,b*) were measured using a spectrophotometer (CIEDE2000 formula) before and after 24 h immersion in red wine (37 °C). Surface roughness (Ra) was analyzed using contact profilometry. Results: The addition of ZnO-NPs increased the lightness (L*) and decreased the a* values in all materials. In resin-based composites, even a 1% concentration of ZnO-NPs caused a color change above the clinical acceptability threshold (ΔE₀₀ > 1.8; observed values ranged from 3.2 to 8.0). After immersion in wine, all materials exhibited further discoloration (ΔE₀₀ up to 12.5 for composites). Surface roughness values increased from 0.42 μm (control composite) to 1.95 μm (3% ZnO-NP-modified GIC). Conclusions: Addition of ZnO-NPs influences the aesthetics and topography of restorative materials. Their concentration must be balanced to maintain visual and surface integrity.