The aim of this research work is to determine the mechanical, morphological and thermal properties of spherical silica (silica-A), amorphous silica (silica-B) and Roselle fiber (RF) reinforced polyurethane (PU) hybrid nanocomposites. The PU nanocomposites were fabricated with different weight percentages, 0.50 to 1 wt% for silica-A and silica-B, while 1–2 wt% for RF. These experiments were systematically designed and analyzed by response surface methodology in a central composite design approach. As per the design of the experiments, the hybrid PU nanocomposites were prepared by using a one shot process. The mathematical models developed to predict the results obtained were in good coherence with the experimental results, and were within 95% confidence levels for tensile and flexural strength. The optimum weight percentage of Roselle, silica-A and silica-B were 2, 0.78 and 1%, respectively. The optimized environmentally friendly hybrid nanocomposite demonstrated exceptional mechanical and thermal properties. © 2019, © 2019 The Author(s). Published by Informa UK Limited, trading as Taylor & Francis Group.