Two different novel high-functional bio-based resins from Methoxylated Sucrose Soyate Polyol (MSSP) and methacrylated epoxidized sucrose soyate (MAESS) were used as matrices for composites. Vinyl ester reinforced with flax fiber and E-glass fiber were also produced as the references to highlight the performance of bio-based composites. An appropriate processing conditions for MSSP and MAESS resins using compression molding was established to fabricate high fiber volume content composites. Mechanical properties of composites were assessed by tensile, flexural, interlaminar shear strength (ILSS), nano-indentation, and impact strength. Scanning Electron Microscopy (SEM) of fractured surfaces of flexural specimens were examined to investigate the fiber-matrix interface behavior. MSSP and MAESS resins reinforced with E-glass fiber performed similarly if not superior to previous bio-based and petroleum-based composites studied Tensile strength and modulus of E-glass reinforced MSSP were higher up to 40% and 75% respectively, compared to existing studies. For flexural strength and modulus 130% and 110% improvements were observed. The tensile strength and modules of MAESS and vinyl ester resins reinforced with E-glass fibers are 532 MPa, 36.79 GPa and 536 MPa, 36.40 GPa, respectively. The impact strength of the composites with MAESS resin reinforced with E-glass fibers was 237 kJ/m2, whereas that of the vinyl ester resin reinforced with same E-glass fiber was 191 kJ/m2. Results of SEM images along with flexural strength, interlaminar shear strength and impact tests revealed better wetting of fibers by matrix, stronger adhesion between fiber and matrix and greater interfacial bonding compared to corresponding E-glass/vinyl ester composites. The composites made from flax fiber with MSSP or MAESS resins achieve similar properties to E-glass/MSSP and E-glass/MAESS in terms of specific mechanical properties. Moreover, flax/MSSP and flax/MAESS composites perform similarly, if not superior to previous bio-based and petroleum based composites studied. A micromechanical model and an analytical approach were also developed to predict the stress relaxation response of the flax/MSSP composite material consisting linear viscoelastic flax fiber and bio-based PU matrix. A good agreement between the micromechanical modeling data and experimental results was observed for the linear viscoelastic response of the bio-based composite.