<p>The effect of nanoparticles on the mechanical properties of flexible polyurethane (PU) foams used in furniture was investigated experimentally. Compression and fatigue tests were performed to observe the mechanical behavior of PU foams reinforced with multilayered graphene and carbon nanotubes (CNTs) with different weight percentages. In addition, the PU foam containing nanoparticles was characterized using scanning electron microscopy (SEM). The effects of the nanoparticles on the morphology and mechanical properties of the foam were discussed. The results showed that the infusion of nanoparticles leads to a significant improvement in mechanical properties. Flexible PU foam containing 0.20 wt% multilayered graphene showed the highest improvement in compression and fatigue tests, while the pure foam showed the lowest improvement. The addition of 0.20 wt% of multilayered graphene increased compressive strength by 84%, while stiffness increased by 193%. Furthermore, the addition of only 0.10 wt% CNTs to the PU foam increased its stiffness by 143%. However, there is no significant difference between the PU foams with 0.10 and 0.15 wt% CNTs. It is also observed that the infusion of nanoparticles positively affects the morphology of the PU foam. In general, the cell shapes become larger and have more cell windows with smaller sizes compared to the pure foam.</p>