The study aim is to develop hybrid filament-wound polymeric composites based on flame retardant polyester resin (UPe) and multi-layer structured glass or combined carbon and glass fibers for use as ablative thermal insulation of rocket motor by wet filament winding technique. The composites have a multi-layered structure consisting of two layers of carbon (CF) or glass woven fabric (GF) and one layer of carbon or glass direct roving (CR or GR, respectively), repeated in three cycles. Structural analysis, performed using FTIR spectroscopy and dynamical-mechanical analysis, confirm highly polymerized network. Lower values of the tanδ peak height indicate improved interfacial adhesion between carbon/glass fibers and UPe. The improvements of thermal insulation index of 37% and erosion rate of 38.6% at 180°C are achieved for combined carbon/glass fiber–based composite compared to the neat UPe. Tensile and interlaminar shear properties are investigated according to the fiber orientation and the highest values of tensile and interlaminar shear strengths are obtained for composites with longitudinal orientation, 417.48 MPa and 22.30 MPa, respectively. Compared to the neat UPe, which degrades after 50 s at 3000°C, the composites are stable up to 192 s.