ZnO nanorods (length 30–150 nm) were synthesized in di(ethylene glycol) using Zn(CH₃COO)₂ as a precursor and para‐toluene sulphonic acid, p‐TSA, as an end‐capping agent. Increasing the concentration of p‐TSA above 0.1 M causes the reduction of the ZnO length. Nanocomposites with poly(methyl methacrylate) were prepared using unmodified nanorods. They enhanced the UV absorption of nanocomposites (~98%) at low ZnO concentrations (0.05–0.1 wt.%), while visible light transparency was high. At concentrations of 1 wt.% and above, nanorods enhanced the thermal stability of nanocomposites. At low concentrations (0.05–0.1 wt.%), they increased the storage modulus of material and shifted T_g towards higher temperatures as shown by dynamic mechanical analysis, DMA, while at higher concentrations (1.0 wt.%) this effect was deteriorated. DMA also showed that spherical ZnO particles have a more pronounced effect on the storage modulus and T_g than nanorods.